scons: Add passthru.py2 for backward compatibility

Not all packages build with Python 3, see #75877. The goal is to get rid
of Python 2 but this approach ensures a smoother transition.

pkgs/misc/drivers/xboxdrv/default.nix

@@ -13,8 +13,8 @@ in stdenv.mkDerivation {
   };
 
   makeFlags = [ "PREFIX=$(out)" ];
-  nativeBuildInputs = [ pkgconfig ];
-  buildInputs = [ scons libX11 libusb1 boost glib dbus-glib ];
+  nativeBuildInputs = [ pkgconfig scons.py2 ];
+  buildInputs = [ libX11 libusb1 boost glib dbus-glib ];
   dontUseSconsInstall = true;
 
   meta = with stdenv.lib; {