Flip the X coordinates when the battle animation is inverted

Fixes the attack animations used by the "Zyklop" in Wolfenhain.

Fix #3417

Author: florianessl

src/battle_animation.cpp

@@ -109,7 +109,7 @@ void BattleAnimation::DrawAt(Bitmap& dst, int x, int y) {
 			continue;
 		}
 
-		SetX(cell.x + x);
+		SetX(invert ? x - cell.x : cell.x + x);
 		SetY(cell.y + y);
 		int sx = cell.cell_id % 5;
 		int sy = cell.cell_id / 5;