default to error checking.

we don't seem to suffer from deadlocking mutexes nor rely on recursive locking, and error checking may even be the default on some platforms, but better to make it explicit so behavior is (more) defined.

src/libbu/semaphore.c

@@ -164,8 +164,13 @@ bu_semaphore_init(unsigned int nsemaphores)
 	sem_bomb(ret);
     }
     for (i=bu_nsemaphores; i < nsemaphores; i++) {
+	pthread_mutexattr_t attr;
 	memset(&bu_semaphores[i], 0, sizeof(struct bu_semaphores));
-	ret = pthread_mutex_init(&bu_semaphores[i].mu,  NULL);
+
+	pthread_mutexattr_init(&attr);
+	pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_ERRORCHECK);
+	ret = pthread_mutex_init(&bu_semaphores[i].mu, &attr);
+	pthread_mutexattr_destroy(&attr);
 	if (ret) {
 	    fprintf(stderr, "bu_semaphore_init(): pthread_mutex_init() failed on [%d] of [%d]\n", i+1, nsemaphores - bu_nsemaphores);
 	    sem_bomb(ret);