perf utils: Check verbose flag properly

It now can have negative value to suppress the message entirely.  So it
needs to check it being positive.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: kernel-team@lge.com
Link: http://lkml.kernel.org/r/20170217081742.17417-3-namhyung@kernel.org
[ Adjust fuzz on tools/perf/util/pmu.c, add > 0 checks in many other places ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/tests/parse-events.c b/tools/perf/tests/parse-events.c
index aa9276b..1dc8380 100644
--- a/tools/perf/tests/parse-events.c
+++ b/tools/perf/tests/parse-events.c
@@ -1808,7 +1808,7 @@ static void debug_warn(const char *warn, va_list params)
 {
 	char msg[1024];
 
-	if (!verbose)
+	if (verbose <= 0)
 		return;
 
 	vsnprintf(msg, sizeof(msg), warn, params);