res_pjsip_phoneprov_provider: Fix leaked OBJ_MULTIPLE iterator.

res_pjsip_phoneprov_provider was using ao2_callback with OBJ_MULTIPLE, then
ignoring the return.  Added OBJ_NODATA flag to prevent a reference leak.

ASTERISK-24935 #close
Reported by: Corey Farrell
Review: https://reviewboard.asterisk.org/r/4578/
........

Merged revisions 433996 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@433997 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_pjsip_phoneprov_provider.c

@@ -353,7 +353,7 @@ static int load_users(void)
 		return 0;
 	}
 
-	ao2_callback(users, OBJ_MULTIPLE, users_apply_handler, sorcery);
+	ao2_callback(users, OBJ_MULTIPLE | OBJ_NODATA, users_apply_handler, sorcery);
 	ao2_ref(users, -1);
 
 	return 0;