Fix name conflict between SoundTouch BOOL and ObjC BOOL.

Source/Core/AudioCommon/OpenALStream.h

@@ -26,9 +26,18 @@
 #include <AL/alext.h>
 #endif
 
+#ifdef __APPLE__
+// Avoid conflict with objc.h (on Windows, ST uses the system BOOL type, so this doesn't work)
+#define BOOL SoundTouch_BOOL
+#endif
+
 #include <soundtouch/SoundTouch.h>
 #include <soundtouch/STTypes.h>
 
+#ifdef __APPLE__
+#undef BOOL
+#endif
+
 // 16 bit Stereo
 #define SFX_MAX_SOURCE          1
 #define OAL_MAX_BUFFERS         32