djgpp: Add darwin support

pkgs/development/compilers/djgpp/default.nix

···
     homepage = "https://www.delorie.com/djgpp/";
     license = lib.licenses.gpl2Plus;
     maintainers = with lib.maintainers; [ hughobrien ];
-    platforms = lib.platforms.linux;
+    platforms = lib.platforms.linux ++ lib.platforms.darwin;
   };
 }

pkgs/top-level/all-packages.nix

···
   dinghy = with python3Packages; toPythonApplication dinghy;
 
   djgpp = djgpp_i586;
-  djgpp_i586 = callPackage ../development/compilers/djgpp { targetArchitecture = "i586"; };
-  djgpp_i686 = lowPrio (callPackage ../development/compilers/djgpp { targetArchitecture = "i686"; });
+  djgpp_i586 = callPackage ../development/compilers/djgpp { targetArchitecture = "i586"; stdenv = gccStdenv; };
+  djgpp_i686 = lowPrio (callPackage ../development/compilers/djgpp { targetArchitecture = "i686"; stdenv = gccStdenv; });
 
   djhtml = python3Packages.callPackage ../development/tools/djhtml { };