webkitgtk: re-enable WPE_RENDERER

Build with WPE renderer is no longer tested upstream
https://bugs.webkit.org/show_bug.cgi?id=238513#c10
and that configuration is extremely buggy since 2.36.0:
https://github.com/NixOS/nixpkgs/issues/169201

Previously it was disabled in c0d053ea0e.

pkgs/development/libraries/webkitgtk/default.nix

@@ -19,6 +19,8 @@
 , gtk3
 , wayland
 , libwebp
+, libwpe
+, libwpe-fdo
 , enchant2
 , xorg
 , libxkbcommon
@@ -82,7 +84,15 @@ stdenv.mkDerivation rec {
       inherit (builtins) storeDir;
       inherit (addOpenGLRunpath) driverLink;
     })
+
     ./libglvnd-headers.patch
+
+    # Hardcode path to WPE backend
+    # https://github.com/NixOS/nixpkgs/issues/110468
+    (substituteAll {
+      src = ./fdo-backend-path.patch;
+      wpebackend_fdo = libwpe-fdo;
+    })
   ];
 
   preConfigure = lib.optionalString (stdenv.hostPlatform != stdenv.buildPlatform) ''
@@ -160,6 +170,8 @@ stdenv.mkDerivation rec {
     libseccomp
     libmanette
     wayland
+    libwpe
+    libwpe-fdo
     xdg-dbus-proxy
   ] ++ lib.optionals systemdSupport [
     systemd
@@ -180,7 +192,6 @@ stdenv.mkDerivation rec {
     "-DENABLE_INTROSPECTION=ON"
     "-DPORT=GTK"
     "-DUSE_LIBHYPHEN=OFF"
-    "-DUSE_WPE_RENDERER=OFF"
     "-DUSE_SOUP2=${cmakeBool (lib.versions.major libsoup.version == "2")}"
     "-DUSE_LIBSECRET=${cmakeBool withLibsecret}"
   ] ++ lib.optionals stdenv.isDarwin [

pkgs/development/libraries/webkitgtk/fdo-backend-path.patch

@@ -0,0 +1,11 @@
+--- a/Source/WebKit/UIProcess/glib/WebProcessPoolGLib.cpp
++++ b/Source/WebKit/UIProcess/glib/WebProcessPoolGLib.cpp
+@@ -89,7 +89,7 @@
+ #if PLATFORM(WAYLAND)
+     if (WebCore::PlatformDisplay::sharedDisplay().type() == WebCore::PlatformDisplay::Type::Wayland) {
+ #if USE(WPE_RENDERER)
+-        wpe_loader_init("libWPEBackend-fdo-1.0.so.1");
++        wpe_loader_init("@wpebackend_fdo@/lib/libWPEBackend-fdo-1.0.so.1");
+         if (AcceleratedBackingStoreWayland::checkRequirements()) {
+             parameters.hostClientFileDescriptor = IPC::Attachment(UnixFileDescriptor(wpe_renderer_host_create_client(), UnixFileDescriptor::Adopt));
+             parameters.implementationLibraryName = FileSystem::fileSystemRepresentation(String::fromLatin1(wpe_loader_get_loaded_implementation_library_name()));