Put a memset in ast_localtime() instead of a couple places in app_voicemail

to prevent the problem everywhere instead of just a couple of places.
(related to issue #10746)


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@82676 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/stdtime/localtime.c

@@ -1142,6 +1142,7 @@ static struct tm *localsub(const time_t *timep, const long offset, struct tm *tm
 struct tm *ast_localtime(const time_t *timep, struct tm *tmp, const char *zone)
 {
 	const struct state *sp = ast_tzset(zone);
+	memset(tmp, 0, sizeof(*tmp));
 	return sp ? localsub(timep, 0L, tmp, sp) : NULL;
 }