[cairo] Pango underline does not work with cairo scale.

[Magicloud Magiclouds]

Hi, the code is following. In a scaled cairo context, the underline is
not scaled as the text. test.png shows that the underline is ever
larger than the "00".
The version of pango is 1.28.0-1. The version of cairo is 1.8.10-4.

#include <cairo.h>
#include <pango/pango.h>

int main () {
  cairo_surface_t * s = cairo_image_surface_create
(CAIRO_FORMAT_ARGB32, 1280, 800);
  cairo_t * c = cairo_create (s);
  cairo_scale (c, 10, 10);
  PangoLayout * l = pango_cairo_create_layout (c);
  pango_layout_set_text (l, "00", 2);
  PangoAttrList * attrs = pango_attr_list_new ();
  pango_attr_list_insert (attrs, pango_attr_underline_new
(PANGO_UNDERLINE_DOUBLE));
  pango_layout_set_attributes (l, attrs);
  cairo_move_to (c, 1, 1);
  pango_cairo_show_layout (c, l);
  cairo_surface_write_to_png (s, "test.png");
  return 0;
}
-- 
竹密岂妨流水过
山高哪阻野云飞