Remove references to four definitions that tb@ deleted in x509.h rev. 1.89

Remove references to four definitions that tb@ deleted in x509.h rev. 1.89
on Jan 10, 2022: X509_EX_V_INIT X509_EX_V_NETSCAPE_HACK
X509_EXT_PACK_STRING X509_EXT_PACK_UNKNOWN.

Mark BN_set_params and BN_get_params as deprecated, unused,
and intentionally undocumented.