Remove X509_CRL_METHOD internals

Remove X509_CRL_METHOD internals

Another complication of dubious value that nobody's ever used. crl_init(),
crl_free() and the meth_data are dead weight, as are their accessors.

Inline def_crl_verify() in X509_CRL_verify() so that the latter becomes
the trivial wrapper of ASN1_item_verify() that one would expect it to be.
It is quite unclear what kind of customization would make sense here...

def_crl_lookup() is renamed into crl_lookup() and its two callers,
X509_CRL_lookup_by_{serial,cert}(), are moved below it so that we
don't need a prototype.

ok jsing