VAAPI: Add VPP class which handles bob deinterlacing
VAAPI: Integrate VPP into VAAPI implementation
VAAPI: Add Flush function
VAAPI: Use shared_ptr::unique() instead of use_count()
VAAPI: Reduce VPP buffer size
VAAPI: Fix VPP compile if libva is too old
VAAPI, sqash me: Fix compile for new 1.2-testing branch