Fix issue 3157123.

Use a Mutex wherever atomic operations were used in AudioTrack,
AudioRecord, AudioFlinger and AudioEffect classes.

Change-Id: I6f55b2cabdcd93d64ef19446735b8f33720f8dbc
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index 5917632..f0ef867 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -785,7 +785,7 @@
               float streamVolumeInternal(int stream) const { return mStreamTypes[stream].volume; }
               void audioConfigChanged_l(int event, int ioHandle, void *param2);
 
-              int  nextUniqueId();
+              int  nextUniqueId_l();
               status_t moveEffectChain_l(int session,
                                      AudioFlinger::PlaybackThread *srcThread,
                                      AudioFlinger::PlaybackThread *dstThread,