Not content with signing negative RSA moduli, still other Estonian IDs have too
many leading zeros. Work around those too.
This workaround will be removed in six months.
BUG=534766
Change-Id: Ica23b1b1499f9dbe39e94cf7b540900860e8e135
Reviewed-on: https://boringssl-review.googlesource.com/5980
Reviewed-by: Adam Langley <agl@google.com>