As of Mac OS X 10.7, Apple deprecated all OpenSSL functions due to
OpenSSL ABI instability. Silence the warnings by using Apple's
CommonCrypto HMAC replacement functions.
[es: reworded commit message; check APPLE_COMMON_CRYPTO instead of
abusing COMMON_DIGEST_FOR_OPENSSL]
Signed-off-by: David Aguilar <davvid@gmail.com> Signed-off-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>