Required for MongoDB >= 2.7.1, see SERVER 12621. Won't work with MongoDB
3.0.2+ because removing the "admin" user will no longer restore the
localhost exception, see SERVER 18415

Avoid use of SHA1 for scram for FIPS

fix hang in TLS handshake

instead use EVP_sha1 so our scram auth is compatible with openssl in FIPS
mode.

Fix typo in prototype argument