Fix overlapping memcpy areas in impeg2_mc_fullx_fully_8x8 am: 7a56a9f0d1 am: 69db39ee2c

Original change: https://android-review.googlesource.com/c/platform/external/libmpeg2/+/2132593

Change-Id: I667d6619e0f31daca6e01daddb44e9a35de2a54a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>