Created library for common audio HAL functions.

Created library for common audio HAL functions.

libaudioutils groups functions that can be used by any audio HAL
implementation.
Current functions are:
- a resampler based on speex resampler.
- an echo reference module providing resampling, buffering and
time stamp management of PCM data between an output stream and an
input stream for use as echo reference by an AEC module.

This commit is the first step consisting of moving code previously in
crespo audio HAL. This C++ code will the be converted to C and stripped from
dependencies to frameworks/base classes for use by all audio HALs.

Change-Id: Ifa51e0c6358c23122a379d7f5d9ce13a65ff0cf0