GitLab

Add callback protector for decode to PCM usage cases.
Move callback protection up earlier for URI decode use case only.

Other:
Remove redundant mCallbackProtector field.
Optimization: on exit from callback protector, only broadcast if !mSafeToEnterCb,
    that is if destroy has requested callback protectors to finish up.
More callback protector logging.
Add callback protector requestCbExit() [no wait], not yet used.

Unrelated:
3rd parameter of adecoder_writeToBufferQueue is always CAudioPlayer * instead of void *.

Change-Id: I57a46acf0e5ecb213540b13ca08098177ad7ad6e