coreaudio: Replaced an int with an SDL_bool.

src/audio/coreaudio/SDL_coreaudio.c

@@ -564,7 +564,7 @@ prepare_audiounit(_THIS, void *handle, int iscapture,
     result = AudioComponentInstanceNew(comp, &this->hidden->audioUnit);
     CHECK_RESULT("AudioComponentInstanceNew");
 
-    this->hidden->audioUnitOpened = 1;
+    this->hidden->audioUnitOpened = SDL_TRUE;
 
     if (iscapture) {  /* have to do EnableIO only for capture devices. */
         UInt32 enable = 1;

src/audio/coreaudio/SDL_coreaudio.h

@@ -44,7 +44,7 @@
 struct SDL_PrivateAudioData
 {
     AudioUnit audioUnit;
-    int audioUnitOpened;
+    SDL_bool audioUnitOpened;
     void *buffer;
     UInt32 bufferOffset;
     UInt32 bufferSize;