Upgrade libmpeg2 to v1.2.0 am: 38399a9b2f am: aad0f41dc0 am: 2ade510f6a am: 706ffd8c88 am: 573df04e08

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

Change-Id: Ie66e3b39d8886212cec402b6b0a27e657081e5a2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>