crossfire-server: fix build due to missing cstdint include

GCC 13 stopped including `cstdint` (and other headers) transitively
in most scenarios, causing build failures in programs that relied
on that behavior.

This change adds a missing `cstdint` include via patch to the
`crossfire-server` source, fixing such a build failure.

pkgs/games/crossfire/add-cstdint-include-to-crossfire-server.patch

@@ -0,0 +1,13 @@
+diff --git a/include/Treasures.h b/include/Treasures.h
+index 614078f..a00b4f6 100644
+--- a/include/Treasures.h
++++ b/include/Treasures.h
+@@ -13,6 +13,8 @@
+ #ifndef TREASURES_H
+ #define TREASURES_H
+ 
++#include <cstdint>
++
+ #include "AssetsCollection.h"
+ 
+ extern "C" {

pkgs/games/crossfire/crossfire-server.nix

@@ -27,6 +27,10 @@ stdenv.mkDerivation rec {
     rev = "r${rev}";
   };
 
+  patches = [
+    ./add-cstdint-include-to-crossfire-server.patch
+  ];
+
   nativeBuildInputs = [ autoconf automake libtool flex perl check pkg-config python39 ];
   hardeningDisable = [ "format" ];