Use mach semaphore rather than posix

macosx/JackPlatformPlug_os.h

@@ -60,12 +60,12 @@ namespace Jack { typedef JackMachThread JackThread; }
 
 /* __JackPlatformSynchro__  client activation */
 #ifndef MY_TARGET_OS_IPHONE
-//#include "JackMachSemaphore.h"
-//namespace Jack { typedef JackMachSemaphore JackSynchro; }
+#include "JackMachSemaphore.h"
+namespace Jack { typedef JackMachSemaphore JackSynchro; }
 
 
-#include "JackPosixSemaphore.h"
-namespace Jack { typedef JackPosixSemaphore JackSynchro; }
+//#include "JackPosixSemaphore.h"
+//namespace Jack { typedef JackPosixSemaphore JackSynchro; }
 
 #endif