perf inject: Fix repipe usage

perf inject: Fix repipe usage

Since commit 14d3d54052539a1e ("perf session: Try to read pipe data from
file") 'perf inject' has started printing "PERFILE2h" when not processing
pipes.

The commit exposed perf to the possiblity that the input is not a pipe
but the 'repipe' parameter gets used. That causes the printing because
perf inject sets 'repipe' to true always.

The 'repipe' parameter of perf_session__new() is used by 2 functions:

	- perf_file_header__read_pipe()
	- trace_report()

In both cases, the functions copy data to STDOUT_FILENO when 'repipe' is
true.

Fix by setting 'repipe' to true only if the output is a pipe.

Fixes: e558a5bd8b74aff4 ("perf inject: Work with files")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Andrew Vagin <avagin@openvz.org>
Link: http://lore.kernel.org/lkml/20210401103605.9000-1-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>