Fix build with libcxx22

See https://github.com/FreeCAD/FreeCAD/issues/28726

Index: src/Mod/Sketcher/App/GeoEnum.h
--- src/Mod/Sketcher/App/GeoEnum.h.orig
+++ src/Mod/Sketcher/App/GeoEnum.h
@@ -129,6 +129,11 @@ class SketcherExport GeoElementId (public)
 
     int posIdAsInt() const;
 
+    inline bool operator<(const GeoElementId& rhs) const {
+        return (GeoId != rhs.GeoId) ? (GeoId < rhs.GeoId)
+                                    : (static_cast<int>(Pos) < static_cast<int>(rhs.Pos));
+    }
+
     /** @brief GeoElementId of the Root Point
      */
     static const GeoElementId RtPnt;
