Remove EVP_add_alg_module() prototype

Remove EVP_add_alg_module() prototype

This function was the unfortunate protagonist in a series of tragic merge
errors resulting in only a short stint of a year and nine months between
OpenSSL 0.9.8j and 1.0.0a actually present in OpenBSD. Then it said good
bye for good, but somehow a prototype came back with 1.0.1g, a famous
version released when there were slightly more pressing things to be
taken care of than a function supporting a config knob whose only purpose
was to turn off fips mode or to error.

from schwarze

PS: The mechanism that it was supposed to provide is still documented in
openssl.cnf(5). I am going remove the relevant bit at some point, but not
today.