[PORT FROM MAIN] VideoDecoderAVC: Flush DPB in VideoDecoderBase::flush()

BZ: 61843

Original libmixvbp_h264 didn't flush DPB when
VideoDecoderBase::flush() was called. For open-GOP
clips who has non-IDR keyframes, a B frame refering
to both the keyframe and the previous GOP may get
decode error.

Change-Id: I5ee2f8b091ac74ccdbb276f26145322bc72415e0
Signed-off-by: Cheng Yao <yao.cheng@intel.com>
Reviewed-on: http://android.intel.com:8080/76397
Tested-by: Tong, BoX <box.tong@intel.com>
Reviewed-by: Tong, BoX <box.tong@intel.com>
Reviewed-by: cactus <cactus@intel.com>
Tested-by: cactus <cactus@intel.com>
7 files changed