printing: Fix origin for scaled, rotated pages

The calls to cairo_translate in
_gtk_print_context_rotate_according_to_orientation,
_gtk_print_context_reverse_according_to_orientation and
_gtk_print_context_translate_into_margin assume an unscaled context.
These functions should therefore be called before scaling the context,
otherwise the origin does not always end up in the top left corner.

https://bugzilla.gnome.org/show_bug.cgi?id=740742