Mark monster-cast enchantments as AUTOMATIC_HIT (duvessa, PowerOfKais…

…hin)

Their to-hit was -1, meaning warlock's mirror almost always reflected
them (every time the to-block roll was positive).

crawl-ref/source/mon-cast.cc

@@ -1310,6 +1310,7 @@ bolt mons_spell_beam(monster* mons, spell_type spell_cast, int power,
 
     if (beam.is_enchantment())
     {
+        beam.hit = AUTOMATIC_HIT;
         beam.glyph = 0;
         beam.name = "";
     }