Implement 3XDAMVDEM Logic for Arrows (#3864)

The Deadly Hunter bow contains the 3XDAMVDEM affix power which isn't present in missiles.cpp, preventing the affix from doing anything altogether. This fix adds the logic from player.cpp in a consistent way with how damage gets handled in melee combat.

Source/missiles.cpp

@@ -238,6 +238,8 @@ bool MonsterMHit(int pnum, int m, int mindam, int maxdam, int dist, missile_id t
 			dam += player._pDamageMod;
 		else
 			dam += player._pDamageMod / 2;
+		if (monster.MData->mMonstClass == MonsterClass::Demon && (player._pIFlags & ISPL_3XDAMVDEM) != 0)
+			dam *= 3;
 	}
 	bool resist = monster.IsResistant(t);
 	if (!shift)