[cairo] BUG REPORT: win32 clip region handling is wrong in cairo 1.10

[Rainman Lee]

the handling of win32 clip region is wrong in cairo 1.10, but it was
right in 1.8.
there is a snippet of my testing codes:

	HRGN w32_hRgn0 = CreateRectRgn(0, 0, 300, 300);
	HRGN w32_hRgn1 = CreateRectRgn(0, 0, 150, 300);
	CombineRgn(w32_hRgn0, w32_hRgn0, w32_hRgn1, RGN_DIFF);
	DeleteObject(w32_hRgn1);
	SelectClipRgn(hdc, w32_hRgn0);

	cairo_surface_t* tarSurface = cairo_win32_surface_create(hdc);
	cairo_t* tarContext = cairo_create(tarSurface);

	cairo_set_source_rgb(tarContext, 1, 0, 0);
	cairo_rectangle(tarContext, 0, 0, 300, 300);
	cairo_fill(tarContext);

the expected result should be a red rectangle at (150, 0, 300, 300),
but in fact, nothing was drawn.