audio: Fix PCM offload for NuPlayer

 * PCM offload is wonderfully broken on NuPlayer in the current CAF
   codebase.  Force the format to an offload format to get it
   working again.

Change-Id: I2ebfa4afc2e0a2bd7e7b6df4595449a2705f1eab
libstagefright: matroska: add missing include dir and header

Change-Id: Ied9c32307e207d171182b83f65368b34c7204651