audio: Add support for tunnel mode recording and compress voip

- Use modulo operator for common block buffer handling. Common block
  size is rounded to power of two. This limitation is avoided with
  modulo operator.
- Add support for tunnel mode recording
- Add support for compress voip

Change-Id: I95cdfff729affd784141487521c9f2f714221d11

audio: check audio mode to enable voice path for VoIP apps

- Add check for MODE_IN_COMMUNICATION to enable voice path
for VoIP applications

Change-Id: Ib603c6321c935d3b1313c2841b09eea932aa13f3

audio: Restrict opening of voip direct output to one instance

Avoid opening of voip direct output track if it is already in use
by another voip application.

Change-Id: I740bbb9e7153c8871c296f1ec5d8d68997391779

audio: check voip input sample rate to allow voip direct output

It is possible that some voip applications request different sample
rates for input and output streams. Avoid opening of voip direct
output if the voip input is already opened with a different sample
rate.

Change-Id: I5669e2a0880ffed0c10cde21da8994c2b47e1878
CRs-fixed: 601785
AudioFlinger: Remove unwanted update of track generation

PlaybackThread::threadLoop unncessarily updates the track generation
before waiting for a pending aync write. This is unncessary and
leads to excess calls to the power manager service for updating
uids.

Change-Id: I1284d79da3be6495acb19a97c81b3ab8db6dbb12
(cherry picked from commit f10fdf3ac4aced7d64bd0d1f05cc886271436685)
(cherry picked from commit 48568df4edf4d9b98c4d05bcfae3770c91f3be7f)
AudioTrack: Fix for race condition

This fixes a race condition between releaseBuffer and flush.

An AudioTrack::releaseBuffer() can be delayed (pre-empted) by
AudioTrack::pause/flush() and ServerProxy::obtainBuffer() calls leading
to a situation where an incorrect position is copied to the cblk

<<Change to be tested>>

Change-Id: I70074d4824ba8c7fa86c9f9ef8cc182de9172ab9
(cherry picked from commit ec237ff01ca194bf0e29933f916a30b8f83c8ace)
(cherry picked from commit 6984cd7b9e99ffa48872cf9316c68d5ae51ad3c5)