Fixes to make Heimdal -Wall -Werror clean

These fixes make developer mode build, at least on Ubuntu.

kdc/misc.c

@@ -140,7 +140,7 @@ _kdc_get_preferred_key(krb5_context context,
     if (config->use_strongest_server_key) {
 	const krb5_enctype *p = krb5_kerberos_enctypes(context);
 
-	for (i = 0; p[i] != ETYPE_NULL; i++) {
+	for (i = 0; p[i] != (krb5_enctype)ETYPE_NULL; i++) {
 	    if (krb5_enctype_valid(context, p[i]) != 0)
 		continue;
 	    ret = hdb_enctype2key(context, &h->entry, p[i], key);