perf header: Use event_name() to get an event name

perf_evsel.name may be not initialized

Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arun Sharma <asharma@fb.com>
Cc: devel@openvz.org
Link: http://lkml.kernel.org/r/1322471015-107825-2-git-send-email-avagin@openvz.org
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/header.c

@@ -388,7 +388,7 @@ static int write_event_desc(int fd, struct perf_header *h __used,
 		/*
 		 * write event string as passed on cmdline
 		 */
-		ret = do_write_string(fd, attr->name);
+		ret = do_write_string(fd, event_name(attr));
 		if (ret < 0)
 			return ret;
 		/*