Remove SHA0

[Sp1l]

In https://github.com/spacemonkeygo/openssl/blob/master/cert.go you're using SHA-0. This standard was never used as collisions were found prior to ratifying it as a standard, please remove it from the code.

Context: OpenSSL 1.1 removed SHA-0 completely (as did LibreSSL). Building breaks on could not determine kind of name for C.EVP_sha

[Sp1l]

This is a duplicate of #43
Nevertheless, SHA-0 is not just phased-out, it should never even have been part of OpenSSL. Anywhere it is used that is in error, you don't want to use a hash that is weaker than MD5.

Simply removing it from the code was sufficient.

[zeebo]

Have you tried on the most recent master? I closed #43 because we have this shim function return null on 1.1:

openssl/shim.c

Line 131 in 1ea168d

const EVP_MD *X_EVP_sha() {

[zeebo]

Although it does look like a bug was introduced where returning NULL will cause problems. That needs to be fixed, regardless, but I don't believe there is a current build failure.