perf tests shell: Skip trace+probe_vfs_getname.sh if built without trace support

perf tests shell: Skip trace+probe_vfs_getname.sh if built without trace support

If perf was built without trace support, the trace+probe_vfs_getname.sh
'perf test' entry fails:

  # perf trace -h
  perf: 'trace' is not a perf-command. See 'perf --help'

  # perf test 64
  64: Check open filename arg using perf trace + vfs_getname: FAILED!

Check trace support, so that we'll skip the test in that case:

  # perf test 64
  64: Check open filename arg using perf trace + vfs_getname: Skip

Signed-off-by: Tommi Rantala <tommi.t.rantala@nokia.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Hendrik Brueckner <brueckner@linux.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kim Phillips <kim.phillips@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20190215134253.11454-1-tt.rantala@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>