fix several issues with nested labels

grub-core/Makefile.core.def

@@ -1208,6 +1208,16 @@ module = {
   common = partmap/bsdlabel.c;
 };
 
+module = {
+  name = part_netbsd;
+  common = partmap/netbsdlabel.c;
+};
+
+module = {
+  name = part_openbsd;
+  common = partmap/openbsdlabel.c;
+};
+
 module = {
   name = part_sunpc;
   common = partmap/sunpc.c;