Fixes stroke-clipped, i.c. of a dashed stroke

Similar to 1f4d05b55c96347aa4240190fda27f951b00c539
 'Fix calling '_cairo_spline_intersect' for in-bounds checking of splines'

Reviewed-by: Bryce Harrington <b.harrington@samsung.com>
cairo_create(): Add finished surface check

Without this change, the following program crashes:

    #include <cairo.h>
    #include <cairo-svg.h>

    int
    main(int argc, char **argv)
    {
      cairo_t *cr;
      cairo_surface_t *finished_surface;

      finished_surface = cairo_svg_surface_create ("/tmp/xxx.svg", 1.0, 1.0);
      cairo_surface_finish (finished_surface);

      cr = cairo_create (finished_surface);
      cairo_destroy (cr);

      cairo_surface_destroy (finished_surface);

      return 0;
    }

Reviewed-by: Bryce Harrington <b.harrington@samsung.com>
Fix SSIZE_T definition problem when making with MSYS on Windows7

Patch provided by Martin Schlemmer <Martin.Schlemmer@nwu.ac.za> on the
mailing list.

Reviewed-by: Bryce Harrington <b.harrington@samsung.com>