aaudio: fix crash from callbacks during close

Move some code from release_l() into a new close_l().
Also stop callbacks before freeing memory in the
FixedBlockReader.

The AudioTrack and AudioRecord callbacks can occur
up until their destructors are called. This can lead
to race conditions if the AAudio stream is dismantled
while the AudioTrack or AudioRecord is still alive.
The AudioRecord was being deleted but not the AudioTrack.
That caused some streams to fail if they were using
a FixedBlockReader, which is used when the app
calls AAudioStreamBuilder_setFramesPerDataCallback().

There was also a problem with a few functions like
AAudioStream_getFramesPerBurst() or AAudioStream_getTimestamp(),
which would crash if called after AAudioStream_release( for
INPUT streams.

Bug: 161914201
Bug: 163165126
Test: see bug for repro of the crash
Test: atest CtsNativeMediaAAudioTestCases
Change-Id: If8f6f6f17ffe06eae98eb8b3930bca08c49a15f8