tes3mp: fix working (#88061)

pkgs/games/openmw/tes3mp.nix

···
     "-DRakNet_LIBRARY_DEBUG=${rakNetLibrary}/lib/libRakNetLibStatic.a"
   ];
 
+  # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95175
+  patches = [
+    ./tes3mp.patch
+  ];
+  NIX_CFLAGS_COMPILE = "-fpermissive";
+
   preConfigure = ''
     substituteInPlace files/version.in \
       --subst-var-by OPENMW_VERSION_COMMITHASH ${compatHash}

pkgs/games/openmw/tes3mp.patch

···
+diff --git a/apps/openmw-mp/Script/Types.hpp b/apps/openmw-mp/Script/Types.hpp
+index be365cfb8..204dcdc7b 100644
+--- a/apps/openmw-mp/Script/Types.hpp
++++ b/apps/openmw-mp/Script/Types.hpp
+@@ -105,7 +105,7 @@ struct ScriptFunctionPointer : public ScriptIdentity
+     void *addr;
+ #if (!defined(__clang__) && defined(__GNUC__))
+     template<typename R, typename... Types>
+-    constexpr ScriptFunctionPointer(Function<R, Types...> addr) : ScriptIdentity(addr), addr((void*)(addr)) {}
++    constexpr ScriptFunctionPointer(Function<R, Types...> addr) : ScriptIdentity(addr), addr(addr) {}
+ #else
+     template<typename R, typename... Types>
+     constexpr ScriptFunctionPointer(Function<R, Types...> addr) : ScriptIdentity(addr), addr(addr) {}

pkgs/top-level/all-packages.nix

···
 
   openmw = libsForQt5.callPackage ../games/openmw { };
 
-  openmw-tes3mp = libsForQt5.callPackage ../games/openmw/tes3mp.nix {
-    openmw = openmw.override {
-      stdenv = gcc8Stdenv;
-      openscenegraph = openscenegraph.override { stdenv = gcc8Stdenv; };
-      mygui = mygui.override { stdenv = gcc8Stdenv; };
-    };
-  };
+  openmw-tes3mp = libsForQt5.callPackage ../games/openmw/tes3mp.nix { };
 
   openraPackages = import ../games/openra pkgs;