qt6.qtwebengine: separate linux-only parts

pkgs/development/libraries/qt-6/modules/qtwebengine.nix

@@ -110,6 +110,13 @@ qtModule {
     substituteInPlace cmake/Functions.cmake \
       --replace "/bin/bash" "${buildPackages.bash}/bin/bash"
 
+    # Patch library paths in sources
+    substituteInPlace src/core/web_engine_library_info.cpp \
+      --replace "QLibraryInfo::path(QLibraryInfo::DataPath)" "\"$out\"" \
+      --replace "QLibraryInfo::path(QLibraryInfo::TranslationsPath)" "\"$out/translations\"" \
+      --replace "QLibraryInfo::path(QLibraryInfo::LibraryExecutablesPath)" "\"$out/libexec\""
+  ''
+  + lib.optionalString stdenv.isLinux ''
     sed -i -e '/lib_loader.*Load/s!"\(libudev\.so\)!"${lib.getLib systemd}/lib/\1!' \
       src/3rdparty/chromium/device/udev_linux/udev?_loader.cc
 
@@ -118,12 +125,6 @@ qtModule {
 
     substituteInPlace src/3rdparty/chromium/ui/events/ozone/layout/xkb/xkb_keyboard_layout_engine.cc \
       --replace "/usr/share/X11/xkb" "${xkeyboard_config}/share/X11/xkb"
-
-    # Patch library paths in sources
-    substituteInPlace src/core/web_engine_library_info.cpp \
-      --replace "QLibraryInfo::path(QLibraryInfo::DataPath)" "\"$out\"" \
-      --replace "QLibraryInfo::path(QLibraryInfo::TranslationsPath)" "\"$out/translations\"" \
-      --replace "QLibraryInfo::path(QLibraryInfo::LibraryExecutablesPath)" "\"$out/libexec\""
   '';
 
   cmakeFlags = [
@@ -143,9 +144,12 @@ qtModule {
     # android only. https://bugreports.qt.io/browse/QTBUG-100293
     # "-DQT_FEATURE_webengine_native_spellchecker=ON"
     "-DQT_FEATURE_webengine_sanitizer=ON"
-    "-DQT_FEATURE_webengine_webrtc_pipewire=ON"
     "-DQT_FEATURE_webengine_kerberos=ON"
-  ] ++ lib.optional enableProprietaryCodecs "-DQT_FEATURE_webengine_proprietary_codecs=ON";
+  ] ++ lib.optionals stdenv.isLinux [
+    "-DQT_FEATURE_webengine_webrtc_pipewire=ON"
+  ] ++ lib.optionals enableProprietaryCodecs [
+    "-DQT_FEATURE_webengine_proprietary_codecs=ON"
+  ];
 
   propagatedBuildInputs = [
     # Image formats
@@ -174,7 +178,7 @@ qtModule {
 
     libevent
     ffmpeg_4
-
+  ] ++ lib.optionals stdenv.isLinux [
     dbus
     zlib
     minizip