libxml2: prepare for multiple versions

pkgs/development/libraries/libxml2/common.nix

@@ -2,7 +2,6 @@
   stdenv,
   darwin,
   lib,
-  fetchFromGitLab,
   pkg-config,
   autoreconfHook,
   python3,
@@ -28,6 +27,10 @@
   gnome,
   testers,
   enableHttp ? false,
+
+  version,
+  src,
+  extraMeta ? { },
 }:
 
 let
@@ -36,8 +39,12 @@ let
   stdenv' = if stdenv.hostPlatform.isDarwin then darwin.bootstrapStdenv else stdenv;
 in
 stdenv'.mkDerivation (finalAttrs: {
+  inherit
+    version
+    src
+    ;
+
   pname = "libxml2";
-  version = "2.14.5";
 
   outputs =
     [
@@ -50,14 +57,6 @@ stdenv'.mkDerivation (finalAttrs: {
     ++ lib.optional (enableStatic && enableShared) "static";
   outputMan = "bin";
 
-  src = fetchFromGitLab {
-    domain = "gitlab.gnome.org";
-    owner = "GNOME";
-    repo = "libxml2";
-    tag = "v${finalAttrs.version}";
-    hash = "sha256-vxKlw8Kz+fgUP6bhWG2+4346WJVzqG0QvPG/BT7RftQ=";
-  };
-
   patches = [
     # Unmerged ABI-breaking patch required to fix the following security issues:
     # - https://gitlab.gnome.org/GNOME/libxslt/-/issues/139
@@ -159,9 +158,6 @@ stdenv'.mkDerivation (finalAttrs: {
     description = "XML parsing library for C";
     license = lib.licenses.mit;
     platforms = lib.platforms.all;
-    maintainers = with lib.maintainers; [
-      jtojnar
-    ];
     pkgConfigModules = [ "libxml-2.0" ];
-  };
+  } // extraMeta;
 })

pkgs/development/libraries/libxml2/default.nix

@@ -0,0 +1,26 @@
+{
+  lib,
+  callPackage,
+  fetchFromGitLab,
+}:
+
+let
+  packages = {
+    libxml2 = callPackage ./common.nix {
+      version = "2.14.5";
+      src = fetchFromGitLab {
+        domain = "gitlab.gnome.org";
+        owner = "GNOME";
+        repo = "libxml2";
+        tag = "v${packages.libxml2.version}";
+        hash = "sha256-vxKlw8Kz+fgUP6bhWG2+4346WJVzqG0QvPG/BT7RftQ=";
+      };
+      extraMeta = {
+        maintainers = with lib.maintainers; [
+          jtojnar
+        ];
+      };
+    };
+  };
+in
+packages

pkgs/top-level/all-packages.nix

@@ -8835,7 +8835,10 @@ with pkgs;
   libxcrypt-legacy = libxcrypt.override { enableHashes = "all"; };
 
   libxkbcommon = libxkbcommon_8;
-  libxml2 = callPackage ../development/libraries/libxml2/common.nix { };
+
+  inherit (callPackage ../development/libraries/libxml2 { })
+    libxml2
+    ;
 
   libxml2Python =
     let