darktable: fix build by using Saxon XSLT processor

The build was failing due to inconsistent ID generation in XSLT
transformations. The generate_prefs.xsl uses generate-id() which
produces different IDs between function declarations and their usage
when using libxslt.

Switching to Saxon XSLT processor resolves this issue as it handles
generate-id() more consistently.

(cherry picked from commit 3bed64fa4e)
https://hydra.nixos.org/build/303791497

pkgs/by-name/da/darktable/package.nix

@@ -2,6 +2,7 @@
   lib,
   stdenv,
   fetchurl,
+  runCommand,
 
   # nativeBuildInputs
   cmake,
@@ -12,6 +13,7 @@
   perl,
   pkg-config,
   wrapGAppsHook3,
+  saxon,
 
   # buildInputs
   SDL2,
@@ -52,7 +54,6 @@
   libtiff,
   libwebp,
   libxml2,
-  libxslt,
   lua,
   util-linux,
   openexr,
@@ -79,6 +80,17 @@
   gitUpdater,
 }:
 
+let
+  # Create a wrapper for saxon to provide saxon-xslt command
+  saxon-xslt = runCommand "saxon-xslt" { } ''
+    mkdir -p $out/bin
+    cat > $out/bin/saxon-xslt << 'EOF'
+    #!/bin/sh
+    exec ${saxon}/bin/saxon "$@"
+    EOF
+    chmod +x $out/bin/saxon-xslt
+  '';
+in
 stdenv.mkDerivation rec {
   version = "5.0.1";
   pname = "darktable";
@@ -97,6 +109,7 @@ stdenv.mkDerivation rec {
     perl
     pkg-config
     wrapGAppsHook3
+    saxon-xslt # Use Saxon instead of libxslt to fix XSLT generate-id() consistency issues
   ];
 
   buildInputs = [
@@ -137,7 +150,6 @@ stdenv.mkDerivation rec {
     libtiff
     libwebp
     libxml2
-    libxslt
     lua
     openexr
     openjpeg