Core Audio output: Potential shutdown fix

The thread wait on shutdown had the potential to lock up waiting for the
thread to shut down. Now it should at least spam the semaphores, so that
the thread should progress to shutdown a lot quicker.

Signed-off-by: Christopher Snowhill <kode54@gmail.com>

Audio/Output/OutputCoreAudio.m

@@ -733,8 +733,11 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
 - (void)stop
 {
     if (stopNext && started && !paused) {
-        while (![[outputController buffer] isEmpty])
+        while (![[outputController buffer] isEmpty]) {
+            [writeSemaphore signal];
+            [readSemaphore signal];
             usleep(500);
+        }
     }
     if (stopNext) {
         stopNext = NO;