chan_sip: Fix segfault during module unload

If a TCP/TLS connection was pending (not accepted and not timed out) during
unload of chan_sip, Asterisk would segfault when trying to send a signal to
a thread whose thread ID hadn't been recorded yet. This commit fixes that by
recording the thread ID before calling the blocking connect() syscall.
This was a regression introduced by 776a14386a.

The above wasn't enough to fix the segfault, which was now delayed to the
point where connect() timed out. Therefore, it was necessary to also remove
the SA_RESTART flag from the SIGURG sigaction so that pthread_kill() could be
used to interruput the connect() syscall.
This was a regression introduced by 5d313f51b9.

ASTERISK-26586 #close

Change-Id: I76fd9d47d56e4264e2629bce8ec15fecba673e7b

channels/chan_sip.c

@@ -2957,6 +2957,7 @@ static void *_sip_tcp_helper_thread(struct ast_tcptls_session_instance *tcptls_s
 		if (!(me = sip_threadinfo_create(tcptls_session, ast_iostream_get_ssl(tcptls_session->stream) ? AST_TRANSPORT_TLS : AST_TRANSPORT_TCP))) {
 			goto cleanup;
 		}
+		me->threadid = pthread_self();
 		ao2_t_ref(me, +1, "Adding threadinfo ref for tcp_helper_thread");
 	} else {
 		struct sip_threadinfo tmp = {
@@ -2964,8 +2965,13 @@ static void *_sip_tcp_helper_thread(struct ast_tcptls_session_instance *tcptls_s
 		};
 
 		if ((!(ca = tcptls_session->parent)) ||
-			(!(me = ao2_t_find(threadt, &tmp, OBJ_POINTER, "ao2_find, getting sip_threadinfo in tcp helper thread"))) ||
-			(!(tcptls_session = ast_tcptls_client_start(tcptls_session)))) {
+			(!(me = ao2_t_find(threadt, &tmp, OBJ_POINTER, "ao2_find, getting sip_threadinfo in tcp helper thread")))) {
+			goto cleanup;
+		}
+
+		me->threadid = pthread_self();
+
+		if (!(tcptls_session = ast_tcptls_client_start(tcptls_session))) {
 			goto cleanup;
 		}
 	}
@@ -2976,7 +2982,6 @@ static void *_sip_tcp_helper_thread(struct ast_tcptls_session_instance *tcptls_s
 		goto cleanup;
 	}
 
-	me->threadid = pthread_self();
 	ast_debug(2, "Starting thread for %s server\n", ast_iostream_get_ssl(tcptls_session->stream) ? "TLS" : "TCP");
 
 	/* set up pollfd to watch for reads on both the socket and the alert_pipe */

main/asterisk.c

@@ -1669,7 +1669,6 @@ static void _urg_handler(int num)
 
 static struct sigaction urg_handler = {
 	.sa_handler = _urg_handler,
-	.sa_flags = SA_RESTART,
 };
 
 static void _hup_handler(int num)