gnustep.gui: fix build

pkgs/desktops/gnustep/base/default.nix

···
       url = "https://github.com/gnustep/libs-base/commit/37913d006d96a6bdcb963f4ca4889888dcce6094.patch";
       sha256 = "PyOmzRIirSKG5SQY+UwD6moCidPb8PXCx3aFgfwxsXE=";
     })
+    # https://github.com/gnustep/libs-base/pull/334
+    (fetchpatch {
+      url = "https://github.com/gnustep/libs-base/commit/b4feee311f2beaf499a5742967213f523de30f16.patch";
+      excludes = [ "ChangeLog" ];
+      hash = "sha256-r0qpxjpEM6y+F/gju6JhpDNxnFJNHFG/mt3NmC1hWrs=";
+    })
   ];
 
   meta = {