slightly suspect changes to get semaphore.c to compile.

The existing code was clearly wrong, but this might not be
the right way to fix it either...

Author: dgrove-oss

src/semaphore.c

@@ -712,10 +712,10 @@ _dispatch_thread_semaphore_create(void)
 	}
 	return s4;
 #elif USE_POSIX_SEM
-	sem_t s4;
-	int ret = sem_init(&s4, 0, 0);
+	sem_t* s4 = malloc(sizeof(sem_t));
+	int ret = sem_init(s4, 0, 0);
 	DISPATCH_SEMAPHORE_VERIFY_RET(ret);
-	return s4;
+	return (_dispatch_thread_semaphore_t)s4;
 #elif USE_WIN32_SEM
 	HANDLE tmp;
 	while (!dispatch_assume(tmp = CreateSemaphore(NULL, 0, LONG_MAX, NULL))) {
@@ -738,8 +738,8 @@ _dispatch_thread_semaphore_dispose(_dispatch_thread_semaphore_t sema)
 	DISPATCH_VERIFY_MIG(kr);
 	DISPATCH_SEMAPHORE_VERIFY_KR(kr);
 #elif USE_POSIX_SEM
-	sem_t s4 = (sem_t)sema;
-	int ret = sem_destroy(&s4);
+	sem_t *s4 = (sem_t*)sema;
+	int ret = sem_destroy(s4);
 	DISPATCH_SEMAPHORE_VERIFY_RET(ret);
 #elif USE_WIN32_SEM
 	// XXX: signal the semaphore?
@@ -762,8 +762,8 @@ _dispatch_thread_semaphore_signal(_dispatch_thread_semaphore_t sema)
 	kern_return_t kr = semaphore_signal(s4);
 	DISPATCH_SEMAPHORE_VERIFY_KR(kr);
 #elif USE_POSIX_SEM
-	sem_t s4 = (sem_t)sema;
-	int ret = sem_post(&s4);
+	sem_t *s4 = (sem_t*)sema;
+	int ret = sem_post(s4);
 	DISPATCH_SEMAPHORE_VERIFY_RET(ret);
 #elif USE_WIN32_SEM
 	int ret;
@@ -788,10 +788,10 @@ _dispatch_thread_semaphore_wait(_dispatch_thread_semaphore_t sema)
 	} while (slowpath(kr == KERN_ABORTED));
 	DISPATCH_SEMAPHORE_VERIFY_KR(kr);
 #elif USE_POSIX_SEM
-	sem_t s4 = (sem_t)sema;
+	sem_t *s4 = (sem_t*)sema;
 	int ret;
 	do {
-		ret = sem_wait(&s4);
+		ret = sem_wait(s4);
 	} while (slowpath(ret != 0));
 	DISPATCH_SEMAPHORE_VERIFY_RET(ret);
 #elif USE_WIN32_SEM