Roll src/third_party/libvpx/source/libvpx/ ec80f88c5..13f984c21 (9 commits)

https://chromium.googlesource.com/webm/libvpx.git/+log/ec80f88c5d05..13f984c2162d

$ git log ec80f88c5..13f984c21 --date=short --no-merges --format='%ad %ae %s'
2021-11-16 jzern vp9 encoder: fix row-mt crash w/thread config change
2021-11-17 kyslov vp9 encoder: fix some integer overflows
2021-11-17 jpegqs replaced bsr() with get_msb() from bitops.h
2021-11-13 jpegqs faster vp8_regular_quantize_b_sse4_1
2021-11-15 jzern encode_api_test.cc: unify kCodecs[] definitions
2021-11-17 johannkoenig MacOS 12 is darwin21
2021-11-15 mikko.koivisto vp9: Fix multiplication overflow
2021-11-11 jzern test/DummyVideoSource::ReallocImage: check img_ alloc
2021-10-27 jzern update libwebm to libwebm-1.0.0.28-20-g206d268

Created with:
  roll-dep src/third_party/libvpx/source/libvpx

Bug: 1261415
Bug: 1270689
Change-Id: I53e60cb1560e8efbc8b3c6869dc028ddcf0145b4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3292451
Reviewed-by: Tom Finegan <tomfinegan@chromium.org>
Commit-Queue: James Zern <jzern@google.com>
Cr-Commit-Position: refs/heads/main@{#944638}