perf header: Fix possible memory leaks in process_group_desc()

After processing all group descriptors or encountering an error, it
frees all descriptors.  However, current logic can leak memory since it
might not traverse all descriptors.

Note that the 'i' can have different value than nr_groups when an error
occurred and it's safe to call free(desc[i].name) for every desc since
we already make it NULL when it's reused for group names.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1384741244-7271-2-git-send-email-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/header.c

@@ -2107,7 +2107,7 @@ static int process_group_desc(struct perf_file_section *section __maybe_unused,
 
 	ret = 0;
 out_free:
-	while ((int) --i >= 0)
+	for (i = 0; i < nr_groups; i++)
 		free(desc[i].name);
 	free(desc);