VE: Enhance MIX to support VAEncPackedHeader.

BZ: 94688

Major modified areas are:
1. Command sequence, add manually built non-VCL header
2. Sequence/Picture/Slice parameters setting

Change-Id: I17d7df288570db1ffabf35ea16c6f5293e776166
Signed-off-by: Chang Ying <ying.chang@intel.com>
Reviewed-on: http://android.intel.com:8080/94561
Reviewed-by: Ding, Haitao <haitao.ding@intel.com>
Tested-by: Ding, Haitao <haitao.ding@intel.com>
Reviewed-by: cactus <cactus@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>
6 files changed