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

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

Change-Id: Id8fb7e0062de1cc2321da48ab6af1e9db795028c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>