Logging should not be done in the callback

[dturner]

Only became apparent when testing the new read/write functionality:

oboe/src/opensles/AudioStreamBuffered.cpp

Line 75 in bc0643f

LOGV("%s() read %d / %d frames from FIFO", __func__, framesTransferred, numFrames);

And

oboe/src/opensles/AudioStreamBuffered.cpp

Line 79 in bc0643f

LOGV("%s() wrote %d / %d frames to FIFO", __func__, framesTransferred, numFrames);

[dturner]

Closing because I've added these as comments in the PR review