Renamed num_ref_ifx_lX_active_minus1 in VAPictureParameterBufferH264 to match the latest spec.

Signed-off-by:  Jonathan Bian <jonathan.bian@intel.com>
Added luma_scale2 and luma_shift2 to VAPictureParameterBufferVC1 to support intensity compensation for P interlace picture

Signed-off-by: Jonathan Bian <jonathan.bian@intel.com>
API: h264 encode: add bitstream writers.

cherry picked from staging d3f85a89804320c4df48b7f288b74ed90614f54d