mm-video: common: Fix race conditions during compilation

The intermediate obj files for the source code files in common
directory were being created in out directory under common location.
Both libOmxVdec and libOmxVenc were referring to the obj files from
this location. Since compilation of both Vdec and Venc can go in
parallel, this results in a compile time race condition. Fix those
by compiling common source files as a static library and including
this library in vdec and venc.

Change-Id: Ie03da79063f21e56c8fe078ac7078b963b2e0c34
9 files changed