perf buildid-list: Fix error return for success

It was always returning -1 (255), confusing test scripts.

Reported-by: Han Pingtian <[e-mail]>
Cc: Frederic Weisbecker <[e-mail]>
Cc: Han Pingtian <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Mike Galbraith <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Stephane Eranian <[e-mail]>
Cc: Tom Zanussi <[e-mail]>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-buildid-list.c

···
 
 static int __cmd_buildid_list(void)
 {
-	int err = -1;
 	struct perf_session *session;
 
 	session = perf_session__new(input_name, O_RDONLY, force, false);
···
 	perf_session__fprintf_dsos_buildid(session, stdout, with_hits);
 
 	perf_session__delete(session);
-	return err;
+	return 0;
 }
 
 int cmd_buildid_list(int argc, const char **argv, const char *prefix __used)