freebsd11_network: Fix race condition leading to lock of deleted mutex.

* Initialize "status" to B_NO_INIT, which will skip the main 'if'
   the first go-around and go straight to the acquire_sem_etc(),
   as we will have be invoked from the callout initializer, and so
   there will of course be no callouts.
 * Actually check the return code of mutex_lock, and do another loop
   iteration (which skips this main 'if' as status will not be one
   of those things.)
 * Correct failure deinitialization order in init_callout().
 * Destroy the mutex after the worker thread exits (this is the real fix.)

Fixes #14660, and other "hang on cursor" / "hang on black screen" /
or possibly even a "hang on rocket" introduced in yesterday's builds.

src/libs/compat/freebsd11_network/callout.cpp

@@ -37,14 +37,15 @@ static bigtime_t sTimeout;
 static status_t
 callout_thread(void* /*data*/)
 {
-	status_t status = B_OK;
+	status_t status = B_NO_INIT;
 
 	do {
 		bigtime_t timeout = B_INFINITE_TIMEOUT;
 
 		if (status == B_TIMED_OUT || status == B_OK) {
 			// scan timers for new timeout and/or execute a timer
-			mutex_lock(&sLock);
+			if ((status = mutex_lock(&sLock)) != B_OK)
+				continue;
 
 			struct callout* c = NULL;
 			while (true) {
@@ -71,7 +72,8 @@ callout_thread(void* /*data*/)
 							&& (c->c_flags & CALLOUT_RETURNUNLOCKED) == 0)
 						mtx_unlock(mutex);
 
-					mutex_lock(&sLock);
+					if ((status = mutex_lock(&sLock)) != B_OK)
+						continue;
 
 					sCurrentCallout = NULL;
 					c = NULL;
@@ -127,10 +129,10 @@ init_callout(void)
 
 	return resume_thread(sThread);
 
-err1:
-	mutex_destroy(&sLock);
 err2:
 	delete_sem(sWaitSem);
+err1:
+	mutex_destroy(&sLock);
 	return status;
 }
 
@@ -139,12 +141,11 @@ void
 uninit_callout(void)
 {
 	delete_sem(sWaitSem);
+
+	wait_for_thread(sThread, NULL);
+
 	mutex_lock(&sLock);
-
 	mutex_destroy(&sLock);
-
-	status_t status;
-	wait_for_thread(sThread, &status);
 }