stagefright: fix AudioRecord callback buffer size

Make sure that the maximum number of frames passed to
AudioSource by the AudioRecord callback always fits within
the maximum buffer size defined by kMaxBufferSize.

Also make sure that the total AudioRecord buffer size is more
than the minimum required.

Change-Id: I26a1f998e0cf75ac88b02e67ec9d8db3c0cca193
1 file changed