This is to help with cryptography.io compatibility. We don't implement
any of the flags (PKCS7_sign checks flags == PKCS7_DETACHED), but
cryptography.io now depends on the constant and PKCS7_SIGNER_INFO type
being available.
(cryptography.io also wants some new functions, but I think it's easier
to stub those out externally for now. If we need to actually enable
those features, we can look at actually implementing more of
PKCS7_sign.)
Change-Id: Id8419e34a68c04d4894417c7d6b13c1952d0bb88
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/46084
Commit-Queue: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: Adam Langley <agl@google.com>