USES=		cmake lua openal

Fix compiling with libc++ and Clang

src/world.cpp:689:53: error: no viable conversion from '__map_iterator<__tree_iterator<__value_type<unsigned int, [...]>, class std::__1::__tree_node<union

      std::__1::__value_type<unsigned int, struct base_item_s *>, void *> *, [...]>>' to '__map_iterator<__tree_iterator<__value_type<const unsigned int, [...]>, class std::__1::__tree_node<union std::__1::__value_type<const unsigned int, struct base_item_s *>, void

      *> *, [...]>>'

    std::map<const uint32_t, base_item_p>::iterator it = global_world.items_tree.find(item_id);

                                                    ^    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

--- src/world.cpp.orig	2017-04-23 13:39:54 UTC

+++ src/world.cpp

@@ -686,7 +686,7 @@ int World_CreateItem(uint32_t item_id, u

 int World_DeleteItem(uint32_t item_id)

 {

-    std::map<const uint32_t, base_item_p>::iterator it = global_world.items_tree.find(item_id);

+    std::map<uint32_t, base_item_p>::iterator it = global_world.items_tree.find(item_id);

     if(it != global_world.items_tree.end())

     {