perf tools: Use zfree to help detect use after free bugs

Several areas already used this technique, so do some audit to
consistently use it elsewhere.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-9sbere0kkplwe45ak6rk4a1f@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/help.c b/tools/perf/util/help.c
index 7b68978..86c37c4 100644
--- a/tools/perf/util/help.c
+++ b/tools/perf/util/help.c
@@ -22,8 +22,8 @@
 	unsigned int i;
 
 	for (i = 0; i < cmds->cnt; ++i)
-		free(cmds->names[i]);
-	free(cmds->names);
+		zfree(&cmds->names[i]);
+	zfree(&cmds->names);
 	cmds->cnt = 0;
 	cmds->alloc = 0;
 }