perf tools: Do not zero sample_id_all for group members

Andi reported following malfunction:

  # perf record -e '{ref-cycles,cycles}:S' -a sleep 1
  # perf script
  non matching sample_id_all

That's because we disable sample_id_all bit for non-sampling group
members. We can't do that, because it needs to be the same over the
whole event list. This patch keeps it untouched again.

Reported-by: Andi Kleen <andi@firstfloor.org>
Tested-by: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180923150420.27327-1-jolsa@kernel.org
Fixes: e9add8bac6c6 ("perf evsel: Disable write_backward for leader sampling group events")
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/attr/test-record-group-sampling

@@ -37,4 +37,3 @@ sample_freq=0
 sample_period=0
 freq=0
 write_backward=0
-sample_id_all=0

tools/perf/util/evsel.c

@@ -956,7 +956,6 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts,
 		attr->sample_freq    = 0;
 		attr->sample_period  = 0;
 		attr->write_backward = 0;
-		attr->sample_id_all  = 0;
 	}
 
 	if (opts->no_samples)