perf stat: Don't display zero tool counts

Andi reported (see link below) a regression when printing the
'duration_time' tool event, where it gets printed as "not counted" for
most of the CPUs, fix it by skipping zero counts for tool events.

Reported-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Andi Kleen <ak@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Claire Jensen <cjense@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/all/ZMlrzcVrVi1lTDmn@tassilo/
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/stat-display.c

@@ -931,6 +931,11 @@ static bool should_skip_zero_counter(struct perf_stat_config *config,
 	 */
 	if (config->aggr_mode == AGGR_THREAD && config->system_wide)
 		return true;
+
+	/* Tool events have the software PMU but are only gathered on 1. */
+	if (evsel__is_tool(counter))
+		return true;
+
 	/*
 	 * Skip value 0 when it's an uncore event and the given aggr id
 	 * does not belong to the PMU cpumask.