See upstream's 5292833132. Syncing just to
reduce the diff for the time being.
Change-Id: I0992d538b283d7348ef1d993973291f5416edce6
Reviewed-on: https://boringssl-review.googlesource.com/18804
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>