perf stat: Modify the group test

Currently nr_members is 0 for an event with no group, however, they
are always a leader of their own group. A later change will make that
count 1 because the event is its own leader. Make the find_stat logic
consistent with this, an improvement suggested by Namhyung Kim.
Suggested-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Florian Fischer <florian.fischer@muhq.space>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kim Phillips <kim.phillips@amd.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Steinar H. Gunderson <sesse@google.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: https://lore.kernel.org/r/20230312021543.3060328-2-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/stat-shadow.c

@@ -163,7 +163,7 @@ static double find_stat(const struct evsel *evsel, int aggr_idx, enum stat_type
 			continue;
 
 		/* Ignore evsels that are part of different groups. */
-		if (evsel->core.leader->nr_members &&
+		if (evsel->core.leader->nr_members > 1 &&
 		    evsel->core.leader != cur->core.leader)
 			continue;
 		/* Ignore evsels with mismatched modifiers. */