[cairo] clip path not getting restored by cairo_restore

[Tim Rowley]

I'm seeing a problem where the clip path is not getting restored
by cairo_restore().  In the following snippet suitable for the
cairo_snippets environment, only the red rectangle inside the
clip path is shown.  The green rectangle outside the save/restore
will not appear unless the cairo_clip() call is commented out.

    cairo_save(cr);

    // upper right quadrent clip
    cairo_new_path(cr);
    cairo_move_to(cr, 0.5, 0.5);
    cairo_line_to(cr, 1.0, 0.5);
    cairo_line_to(cr, 1.0, 0.0);
    cairo_line_to(cr, 0.5, 0.0);
    cairo_close_path(cr);
    cairo_clip(cr);

    // upper right quadrent rectangle (red)
    cairo_new_path(cr);
    cairo_move_to(cr, 0.5, 0.5);
    cairo_line_to(cr, 1.0, 0.5);
    cairo_line_to(cr, 1.0, 0.0);
    cairo_line_to(cr, 0.5, 0.0);
    cairo_close_path(cr);
    cairo_set_rgb_color (cr, 1, 0, 0);
    cairo_fill(cr);

    cairo_restore(cr);

    // lower left quadrent rectangle (green)
    cairo_new_path(cr);
    cairo_move_to(cr, 0.0, 1.0);
    cairo_line_to(cr, 0.5, 1.0);
    cairo_line_to(cr, 0.5, 0.5);
    cairo_line_to(cr, 0.0, 0.5);
    cairo_close_path(cr);
    cairo_set_rgb_color (cr, 0, 1, 0);
    cairo_fill(cr);