Upgrade libmpeg2 to v1.2.0 am: 38399a9b2f am: aad0f41dc0 am: 2ade510f6a am: 706ffd8c88

Original change: https://android-review.googlesource.com/c/platform/external/libmpeg2/+/2698473

Change-Id: I010bc009e555b9bc67da2cb4aa2df6158067cad2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>