libperf: Move nr_members from perf's evsel to libperf's perf_evsel

Move the nr_members member from perf's evsel to libperf's perf_evsel.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.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/20190721112506.12306-60-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index e258e98..d4288dc 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -436,7 +436,7 @@ static size_t hists__fprintf_nr_sample_events(struct hists *hists, struct report
 	ret = fprintf(fp, "# Samples: %lu%c", nr_samples, unit);
 	if (evname != NULL) {
 		ret += fprintf(fp, " of event%s '%s'",
-			       evsel->nr_members > 1 ? "s" : "", evname);
+			       evsel->core.nr_members > 1 ? "s" : "", evname);
 	}
 
 	if (rep->time_str)