Properly update 'maxtype'

'maxtype' should be checked to see if it should be updated whenever
a type is added to the type map.

(cherry picked from commit e84615629f)

lib/dns/zoneverify.c

@@ -959,6 +959,9 @@ verifynode(vctx_t *vctx, const dns_name_t *name, dns_dbnode_t *node,
 		{
 			if (rdataset.type == dns_rdatatype_ns) {
 				dns_nsec_setbit(types, rdataset.type, 1);
+				if (rdataset.type > maxtype) {
+					maxtype = rdataset.type;
+				}
 			}
 			result = check_no_rrsig(vctx, &rdataset, name, node);
 			if (result != ISC_R_SUCCESS) {
@@ -968,6 +971,9 @@ verifynode(vctx_t *vctx, const dns_name_t *name, dns_dbnode_t *node,
 			}
 		} else {
 			dns_nsec_setbit(types, rdataset.type, 1);
+			if (rdataset.type > maxtype) {
+				maxtype = rdataset.type;
+			}
 		}
 		dns_rdataset_disassociate(&rdataset);
 		result = dns_rdatasetiter_next(rdsiter);