Fix compilation error when the resource manager is disabled.

miniaudio.h

@@ -10985,7 +10985,9 @@ typedef struct
     ma_uint64 loopPointBegInPCMFrames;
     ma_uint64 loopPointEndInPCMFrames;
     ma_bool32 isLooping;
+#ifndef MA_NO_RESOURCE_MANAGER
     ma_resource_manager_pipeline_notifications initNotifications;
+#endif
     ma_fence* pDoneFence;                       /* Deprecated. Use initNotifications instead. Released when the resource manager has finished decoding the entire sound. Not used with streams. */
 } ma_sound_config;