EndCall for incoming call while on hold doesn't close both legs on a skinny phone

Fixes #FS-5232, thanks to Nathan Neulinger for the patch

src/mod/endpoints/mod_skinny/skinny_server.c

@@ -1820,6 +1820,9 @@ switch_status_t skinny_handle_soft_key_event_message(listener_t *listener, skinn
 			session = skinny_profile_find_session(listener->profile, listener, &line_instance, call_id);
 			if(session) {
 				channel = switch_core_session_get_channel(session);
+				if (switch_channel_test_flag(channel, CF_HOLD)) {
+					switch_ivr_unhold(session);
+				}
 				switch_channel_hangup(channel, SWITCH_CAUSE_NORMAL_CLEARING);
 			}
 			break;