perf auxtrace: For reporting purposes, un-group AUX area event

perf auxtrace: For reporting purposes, un-group AUX area event

An AUX area event must be the group leader when recording traces in
sample mode, but that does not produce the expected results from
'perf report' because it expects the leader to provide samples.

Rather than teach 'perf report' about AUX area sampling, un-group the
AUX area event during processing, making the 2nd event the leader.

Example:

 $ perf record -e '{intel_pt//u,branch-misses:u}' -c 1 uname
 Linux
 [ perf record: Woken up 1 times to write data ]
 [ perf record: Captured and wrote 0.080 MB perf.data ]

 Before:

 $ perf report

 Samples: 800  of events 'anon group { intel_pt//u, branch-misses:u }', Event count (approx.): 800
        Children              Self  Command  Shared Object     Symbol
     0.00%  47.50%     0.00%  47.50%  uname    libc-2.28.so      [.] _dl_addr
     0.00%  16.38%     0.00%  16.38%  uname    ld-2.28.so        [.] __GI___tunables_init
     0.00%  54.75%     0.00%   4.75%  uname    ld-2.28.so        [.] dl_main
     0.00%   3.12%     0.00%   3.12%  uname    ld-2.28.so        [.] _dl_map_object_from_fd
     0.00%   2.38%     0.00%   2.38%  uname    ld-2.28.so        [.] strcmp
     0.00%   2.25%     0.00%   2.25%  uname    ld-2.28.so        [.] _dl_check_map_versions
     0.00%   2.00%     0.00%   2.00%  uname    ld-2.28.so        [.] _dl_important_hwcaps
     0.00%   2.00%     0.00%   2.00%  uname    ld-2.28.so        [.] _dl_map_object_deps
     0.00%  51.50%     0.00%   1.50%  uname    ld-2.28.so        [.] _dl_sysdep_start
     0.00%   1.25%     0.00%   1.25%  uname    ld-2.28.so        [.] _dl_load_cache_lookup
     0.00%  51.12%     0.00%   1.12%  uname    ld-2.28.so        [.] _dl_start
     0.00%  50.88%     0.00%   1.12%  uname    ld-2.28.so        [.] do_lookup_x
     0.00%  50.62%     0.00%   1.00%  uname    ld-2.28.so        [.] _dl_lookup_symbol_x
     0.00%   1.00%     0.00%   1.00%  uname    ld-2.28.so        [.] _dl_map_object
     0.00%   1.00%     0.00%   1.00%  uname    ld-2.28.so        [.] _dl_next_ld_env_entry
     0.00%   0.88%     0.00%   0.88%  uname    ld-2.28.so        [.] _dl_cache_libcmp
     0.00%   0.88%     0.00%   0.88%  uname    ld-2.28.so        [.] _dl_new_object
     0.00%  50.88%     0.00%   0.88%  uname    ld-2.28.so        [.] _dl_relocate_object
     0.00%   0.62%     0.00%   0.62%  uname    ld-2.28.so        [.] _dl_init_paths
     0.00%   0.62%     0.00%   0.62%  uname    ld-2.28.so        [.] _dl_name_match_p
     0.00%   0.50%     0.00%   0.50%  uname    ld-2.28.so        [.] get_common_indeces.constprop.1
     0.00%   0.50%     0.00%   0.50%  uname    ld-2.28.so        [.] memmove
     0.00%   0.50%     0.00%   0.50%  uname    ld-2.28.so        [.] memset
     0.00%   0.50%     0.00%   0.50%  uname    ld-2.28.so        [.] open_verify.constprop.11
     0.00%   0.38%     0.00%   0.38%  uname    ld-2.28.so        [.] _dl_check_all_versions
     0.00%   0.38%     0.00%   0.38%  uname    ld-2.28.so        [.] _dl_find_dso_for_object
     0.00%   0.38%     0.00%   0.38%  uname    ld-2.28.so        [.] init_tls
     0.00%   0.25%     0.00%   0.25%  uname    ld-2.28.so        [.] __tunable_get_val
     0.00%   0.25%     0.00%   0.25%  uname    ld-2.28.so        [.] _dl_add_to_namespace_list
     0.00%   0.25%     0.00%   0.25%  uname    ld-2.28.so        [.] _dl_determine_tlsoffset
     0.00%   0.25%     0.00%   0.25%  uname    ld-2.28.so        [.] _dl_discover_osversion
     0.00%   0.25%     0.00%   0.25%  uname    ld-2.28.so        [.] calloc@plt
     0.00%   0.25%     0.00%   0.25%  uname    ld-2.28.so        [.] malloc
     0.00%   0.25%     0.00%   0.25%  uname    ld-2.28.so        [.] malloc@plt
     0.00%   0.25%     0.00%   0.25%  uname    libc-2.28.so      [.] _nl_load_locale_from_archive
     0.00%   0.25%     0.00%   0.25%  uname    [unknown]         [k] 0xffffffffa3a00010
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] __libc_scratch_buffer_set_array_size
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] _dl_allocate_tls_storage
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] _dl_catch_exception
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] _dl_setup_hash
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] _dl_sort_maps
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] _dl_sysdep_read_whole_file
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] access
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] calloc
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] mmap64
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] openaux
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] rtld_lock_default_lock_recursive
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] rtld_lock_default_unlock_recursive
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] strchr
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] strlen
     0.00%   0.12%     0.00%   0.12%  uname    ld-2.28.so        [.] 0x0000000000001080
     0.00%   0.12%     0.00%   0.12%  uname    libc-2.28.so      [.] __strchrnul_avx2
     0.00%   0.12%     0.00%   0.12%  uname    libc-2.28.so      [.] _nl_normalize_codeset
     0.00%   0.12%     0.00%   0.12%  uname    libc-2.28.so      [.] malloc
     0.00%   0.12%     0.00%   0.12%  uname    [unknown]         [k] 0xffffffffa3a011f0
     0.00%  50.00%     0.00%   0.00%  uname    ld-2.28.so        [.] _dl_start_user
     0.00%  50.00%     0.00%   0.00%  uname    [unknown]         [.] 0000000000000000

 After:

 Samples: 800  of event 'branch-misses:u', Event count (approx.): 800
  Children      Self  Command  Shared Object     Symbol
    54.75%     4.75%  uname    ld-2.28.so        [.] dl_main
    51.50%     1.50%  uname    ld-2.28.so        [.] _dl_sysdep_start
    51.12%     1.12%  uname    ld-2.28.so        [.] _dl_start
    50.88%     0.88%  uname    ld-2.28.so        [.] _dl_relocate_object
    50.88%     1.12%  uname    ld-2.28.so        [.] do_lookup_x
    50.62%     1.00%  uname    ld-2.28.so        [.] _dl_lookup_symbol_x
    50.00%     0.00%  uname    ld-2.28.so        [.] _dl_start_user
    50.00%     0.00%  uname    [unknown]         [.] 0000000000000000
    47.50%    47.50%  uname    libc-2.28.so      [.] _dl_addr
    16.38%    16.38%  uname    ld-2.28.so        [.] __GI___tunables_init
     3.12%     3.12%  uname    ld-2.28.so        [.] _dl_map_object_from_fd
     2.38%     2.38%  uname    ld-2.28.so        [.] strcmp
     2.25%     2.25%  uname    ld-2.28.so        [.] _dl_check_map_versions
     2.00%     2.00%  uname    ld-2.28.so        [.] _dl_important_hwcaps
     2.00%     2.00%  uname    ld-2.28.so        [.] _dl_map_object_deps
     1.25%     1.25%  uname    ld-2.28.so        [.] _dl_load_cache_lookup
     1.00%     1.00%  uname    ld-2.28.so        [.] _dl_map_object
     1.00%     1.00%  uname    ld-2.28.so        [.] _dl_next_ld_env_entry
     0.88%     0.88%  uname    ld-2.28.so        [.] _dl_cache_libcmp
     0.88%     0.88%  uname    ld-2.28.so        [.] _dl_new_object
     0.62%     0.62%  uname    ld-2.28.so        [.] _dl_init_paths
     0.62%     0.62%  uname    ld-2.28.so        [.] _dl_name_match_p
     0.50%     0.50%  uname    ld-2.28.so        [.] get_common_indeces.constprop.1
     0.50%     0.50%  uname    ld-2.28.so        [.] memmove
     0.50%     0.50%  uname    ld-2.28.so        [.] memset
     0.50%     0.50%  uname    ld-2.28.so        [.] open_verify.constprop.11
     0.38%     0.38%  uname    ld-2.28.so        [.] _dl_check_all_versions
     0.38%     0.38%  uname    ld-2.28.so        [.] _dl_find_dso_for_object
     0.38%     0.38%  uname    ld-2.28.so        [.] init_tls
     0.25%     0.25%  uname    ld-2.28.so        [.] __tunable_get_val
     0.25%     0.25%  uname    ld-2.28.so        [.] _dl_add_to_namespace_list
     0.25%     0.25%  uname    ld-2.28.so        [.] _dl_determine_tlsoffset
     0.25%     0.25%  uname    ld-2.28.so        [.] _dl_discover_osversion
     0.25%     0.25%  uname    ld-2.28.so        [.] calloc@plt
     0.25%     0.25%  uname    ld-2.28.so        [.] malloc
     0.25%     0.25%  uname    ld-2.28.so        [.] malloc@plt
     0.25%     0.25%  uname    libc-2.28.so      [.] _nl_load_locale_from_archive
     0.25%     0.25%  uname    [unknown]         [k] 0xffffffffa3a00010
     0.12%     0.12%  uname    ld-2.28.so        [.] __libc_scratch_buffer_set_array_size
     0.12%     0.12%  uname    ld-2.28.so        [.] _dl_allocate_tls_storage
     0.12%     0.12%  uname    ld-2.28.so        [.] _dl_catch_exception
     0.12%     0.12%  uname    ld-2.28.so        [.] _dl_setup_hash
     0.12%     0.12%  uname    ld-2.28.so        [.] _dl_sort_maps
     0.12%     0.12%  uname    ld-2.28.so        [.] _dl_sysdep_read_whole_file
     0.12%     0.12%  uname    ld-2.28.so        [.] access
     0.12%     0.12%  uname    ld-2.28.so        [.] calloc
     0.12%     0.12%  uname    ld-2.28.so        [.] mmap64
     0.12%     0.12%  uname    ld-2.28.so        [.] openaux
     0.12%     0.12%  uname    ld-2.28.so        [.] rtld_lock_default_lock_recursive
     0.12%     0.12%  uname    ld-2.28.so        [.] rtld_lock_default_unlock_recursive
     0.12%     0.12%  uname    ld-2.28.so        [.] strchr
     0.12%     0.12%  uname    ld-2.28.so        [.] strlen
     0.12%     0.12%  uname    ld-2.28.so        [.] 0x0000000000001080
     0.12%     0.12%  uname    libc-2.28.so      [.] __strchrnul_avx2
     0.12%     0.12%  uname    libc-2.28.so      [.] _nl_normalize_codeset
     0.12%     0.12%  uname    libc-2.28.so      [.] malloc
     0.12%     0.12%  uname    [unknown]         [k] 0xffffffffa3a011f0

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-8-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>