stagefright-plugins: Audio output port reconfiguration support

 * Add support for reconfiguring the audio output port (PCM) on the
   fly. This enables us to easily control both high resolution
   output as well as downsampling.

Change-Id: Ic5ea3efc966b0da2d62041fa0de2e422c1f9f7fc
stagefright-plugins: Allow use of HW codecs for Windows Media

 * We will still fall back to FFMPEG if these fail.

Change-Id: I74287268f6782e69e0bee624368a85837d2c7969