perf stat: Fix aggreate counter reading accounting

Introduced in: c52b12ed, when this sequence:

  count[0] = count[1] = count[2] = 0;

Was replaced with:

  aggr->val = 0;

Which is equivalent to zeroing just the first entry in the 'count'
array.

Fix it by zeroing the three entries with:

  aggr->val = aggr->ena = aggr->run = 0;
Reported-by: NIngo Molnar <mingo@elte.hu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/evsel.c

@@ -90,7 +90,7 @@ int __perf_evsel__read(struct perf_evsel *evsel,
 	int cpu, thread;
 	struct perf_counts_values *aggr = &evsel->counts->aggr, count;
 
-	aggr->val = 0;
+	aggr->val = aggr->ena = aggr->run = 0;
 
 	for (cpu = 0; cpu < ncpus; cpu++) {
 		for (thread = 0; thread < nthreads; thread++) {