/*
 * Fill an Imlib2::Polygon with the specified color
 *
 * Examples:
 *   # create an filled green diamond polygon
 *   square = Imlib2.Polygon.new [50, 10], [70, 30], [50, 50], [30, 30]
 *   image.fill_poly square, false, Imlib2::Color::GREEN
 *
 */
static VALUE image_fill_poly(int argc, VALUE *argv, VALUE self) {