external/boringssl: Sync to a9670a8b476470e6f874fef3554e8059683e1413. am: b15b125fe3 am: b4ecdf9a89 am: 5f8ebf8037 am: 6df2f14891

Original change: https://android-review.googlesource.com/c/platform/external/boringssl/+/1882472

Change-Id: If45b046b235744839f293d75a56c6cdc03de7b5d