external/libgav1: update to v0.16.3 am: 81461368d4

Original change: https://android-review.googlesource.com/c/platform/external/libgav1/+/1676768

Change-Id: I69cad99291a6817597bcd9e22fdfb62ed183f089
Merged-In: I87f41df0e6aa1bea210b43e4bff6487a9cb83269
Merged-In: Iac6db2394c79ba0314f26eec4c391e3c04769545
(cherry picked from commit 13ed79329b963d5057e84274c6142096ad2553c4)
189 files changed