Remove get_optional_pkey_id() - it is a hack that existed due to GOST
only sometimes being available... and when it was available it was via
the crypto engine. GOST is now part of libcrypto proper.

Instead of trying to do EVP PKEY lookups via string literals and the
ASN1 interfaces, lookup the methods directly using the appropriate NID.

ok bcook@
Remove OPENSSL_FIPSCANISTER mentions.