nacl: Patched to compile.

src/audio/nacl/SDL_naclaudio.c

@@ -50,7 +50,7 @@ static void nacl_audio_callback(void* samples, uint32_t buffer_size, PP_TimeDelt
     
     SDL_LockMutex(private->mutex);  /* !!! FIXME: is this mutex necessary? */
 
-    if (SDL_AtomicGet(&this->enabled) && !SDL_AtomicGet(&this->paused)) {
+    if (SDL_AtomicGet(&_this->enabled) && !SDL_AtomicGet(&_this->paused)) {
         if (_this->convert.needed) {
             SDL_LockMutex(_this->mixer_lock);
             (*_this->spec.callback) (_this->spec.userdata,