Enable building blscfg module on xen and xen_pvh

Building blscfg module for Xen targets makes it possible to include them
in custom pvgrub2 and pvhgrub2 images. Those are then used to boot PV and
PVH domUs.

Signed-off-by: Matyáš Kroupa <[email protected]>

Author: krouma

grub-core/Makefile.core.def

@@ -880,6 +880,8 @@ module = {
   enable = efi;
   enable = i386_pc;
   enable = emu;
+  enable = xen;
+  enable = i386_xen_pvh;
 };
 
 module = {