ruffle: add postInstall phase for desktop files on Linux

Author: normalcea

pkgs/by-name/ru/ruffle/package.nix

@@ -66,6 +66,12 @@ rustPlatform.buildRustPackage {
 
   dontWrapGApps = true;
 
+  postInstall = lib.optionalString stdenv.hostPlatform.isLinux ''
+    install -Dm644 -t "$out/share/icons/hicolor/scalable/apps/" desktop/packages/linux/rs.ruffle.Ruffle.svg
+    install -Dm644 -t "$out/share/applications/" desktop/packages/linux/rs.ruffle.Ruffle.desktop
+    install -Dm644 -t "$out/share/metainfo/" desktop/packages/linux/rs.ruffle.Ruffle.metainfo.xml
+  '';
+
   preFixup = lib.optionalString stdenv.hostPlatform.isLinux ''
     patchelf $out/bin/ruffle_desktop \
       --add-needed libxkbcommon-x11.so \