perf tools: Add missing check for failure in a zalloc() call

Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1485952447-7013-3-git-send-email-treeze.taeung@gmail.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/parse-events.c

@@ -211,6 +211,8 @@ struct tracepoint_path *tracepoint_id_to_path(u64 config)
 				closedir(evt_dir);
 				closedir(sys_dir);
 				path = zalloc(sizeof(*path));
+				if (!path)
+					return NULL;
 				path->system = malloc(MAX_EVENT_LENGTH);
 				if (!path->system) {
 					free(path);