try to fix variable / escaping problem

pkgs/openmw/tes3mp.nix

@@ -122,18 +122,18 @@ symlinkJoin rec {
 
   paths = [ unwrapped ];
 
+  cfgDir="\\$HOME/.config/openmw";
+
   # crudini --merge will create the file if it doesn't exist
   postBuild = ''
     mkdir -p $out/bin
 
-    dir=\''${XDG_CONFIG_HOME:-\$HOME/.config}/openmw
-
     makeWrapper ${unwrapped}/libexec/tes3mp-browser $out/bin/tes3mp-browser \
       --chdir "$out/bin"
 
     makeWrapper ${unwrapped}/libexec/tes3mp-server $out/bin/tes3mp-server \
-      --run "mkdir -p $dir" \
-      --run "${crudini}/bin/crudini --merge $dir/${cfgFile.name} < ${cfgFile}" \
+      --run "mkdir -p ${cfgDir}" \
+      --run "${crudini}/bin/crudini --merge ${cfgDir}/${cfgFile.name} < ${cfgFile}" \
       --chdir "$out/bin"
   '';
 }