Remove EVP_add_{cipher,digest}() from public API

Remove EVP_add_{cipher,digest}() from public API

Ciphers and digests are now handled in a static lookup table and no
longer by the associative array that used to underlie the OBJ_NAME API.
Adding ciphers is no longer possible. What uses this API does so for
historic reasons coming from a time where SHA-2 and some AES variants
needed to be enabled explicitly. Ports doing this (PHP and DANE code)
were fixed.

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