libphoenix: fix mutexing in pthread_create

Fixes: phoenix-rtos/phoenix-rtos-project/issues/891

JIRA: RTOS-651

pthread/pthread.c

@@ -260,6 +260,8 @@ int pthread_create(pthread_t *thread, const pthread_attr_t *attr,
 	ctx->cancelstate = PTHREAD_CANCEL_ENABLE;
 	*thread = (pthread_t)ctx;
 
+	mutexLock(pthread_common.pthread_list_lock);
+
 	int err = beginthreadex(start_point, attrs->priority, stack,
 		attrs->stacksize, (void *)ctx, &ctx->id);
 
@@ -269,14 +271,14 @@ int pthread_create(pthread_t *thread, const pthread_attr_t *attr,
 		thread = NULL;
 	}
 	else if (ctx->detached == PTHREAD_CREATE_JOINABLE) {
-		mutexLock(pthread_common.pthread_list_lock);
-		if (pthread_common.pthread_list != NULL && pthread_common.pthread_list->id == 0)
+		if (pthread_common.pthread_list != NULL && pthread_common.pthread_list->id == 0) {
 			pthread_common.pthread_list = NULL;
-
+		}
 		LIST_ADD(&pthread_common.pthread_list, ctx);
-		mutexUnlock(pthread_common.pthread_list_lock);
 	}
 
+	mutexUnlock(pthread_common.pthread_list_lock);
+
 	return -err;
 }