Don't limit anvil stack size.

After the changes in c549609d anvils started incorrectly limiting their
inputs to single item stacks. Vanilla allows for full size stacks here and
this is useful for using materials to repair items so now we do too.

src/main/java/net/minecraft/server/ContainerAnvilInventory.java

@@ -43,7 +43,6 @@ public class ContainerAnvilInventory extends InventorySubcontainer { // CraftBuk
     ContainerAnvilInventory(ContainerAnvil containeranvil, String s, boolean flag, int i) {
         super(s, flag, i);
         this.a = containeranvil;
-        this.setMaxStackSize(1); // CraftBukkit
     }
 
     // CraftBukkit start - override inherited maxStack from InventorySubcontainer