screenrecord: Add option to mux in audio from the mic

Adding the --audio option at the command line will allow
audio to be recorded from the microphone and muxed in with
the video.

Change-Id: Id47974ca31f65d78f7712734c59db7fc05ee9781
stagefright: Fix "add an extra buffer to ANW's BUfferQueue"

OMAP devices, such as maguro, don't work properly with an extra buffer.
This fixes the commit 2bce3e06f60a8d60c81261b0438d0cc6f2bbe7d1.

Change-Id: Id78442831e95b6021ea8b6d3648678db094f4565