Merge "backport vp8/9 unsigned int overflow fix" am: c03eb8c06c am: 7196a556b5

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/libvpx/+/14490237

Change-Id: I65f512cff2ba5a829bba1e90c788d5d746e857c7