Remove deprecated dns_db_rpz_*() methods

As well as the function wrappers, their slots have been removed from
the dns_dbmethods table.

lib/dns/sdlz.c

@@ -1247,8 +1247,6 @@ static dns_dbmethods_t sdlzdb_methods = {
 	NULL,				      /* resigned */
 	NULL,				      /* isdnssec */
 	NULL,				      /* getrrsetstats */
-	NULL,				      /* rpz_attach */
-	NULL,				      /* rpz_ready */
 	findnodeext,	findext,	NULL, /* setcachestats */
 	NULL,				      /* hashsize */
 	NULL,				      /* nodefullname */