These behave like EVP_AEAD_CTX_{seal,open} respectively, but receive
ciphertext and authentication tag as separate arguments, rather than one
contiguous out or in buffer.
Change-Id: Ia4f1b83424bc7067c55dd9e5a68f18061dab4d07
Reviewed-on: https://boringssl-review.googlesource.com/16924
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>