Another fix for #K4317 - monster grudge

Undead monsters created by the level creation routine do not grudge
other (zombifiable) monsters created during the level creation.

This of course doesn't prevent the grudge happening with monsters
created during gameplay.

Invalidates saves and bones.

src/makemon.c

@@ -1295,6 +1295,7 @@ makemon(
 
     place_monster(mtmp, x, y);
     mtmp->mcansee = mtmp->mcanmove = TRUE;
+    mtmp->mgenmklev = gi.in_mklev;
     mtmp->seen_resistance = M_SEEN_NOTHING;
     mtmp->mpeaceful = (mmflags & MM_ANGRY) ? FALSE : peace_minded(ptr);
     if ((mmflags & MM_MINVIS) != 0) /* for ^G */