screenrecord: Add audio support

Adds audio recording to the screenrecord system. Note that
while recording, the audio is muted from the device output,
and that the audio volume is controlled separately (so make
sure to turn up your volume if you hear nothing).
Audio from the microphone can also be recorded by adding
--microphone to the command line.

Change-Id: I97dfcaf3d93b786c5466e1f4215549e3d015bcf0
screenrecord: Enable SUBMIX_IN as well and cleanup on exit

While on Nexus 5/Nexus 7 (AOSP QCOM audio), trying to turn on
SUBMIX_IN fails and is not needed, it is required on Find 5
and N1 (CAF QCOM audio), or otherwise SUBMIX_OUT won't turn
on.
We also now release the audio routing as it wouldn't revive
the audio speakers otherwise.

Change-Id: I0f80a232304733e0b0a834b188b8cfa5b88915f3
[2/3] av: Audio Themes Support

On the Java side, Android has support for both a
Video Record Start sound, and a different Video
Record Stop sound. However, this part here only
supports one video recording sound.
We added support for RECORDING_STOP sound (by default,
the same as RECORDING).

Change-Id: Iaebddd8ebf8b21633e802589a4a6175492df8f29