Add a fake STEPPER function that is used for drawing scrollbar steppers,

Add a fake STEPPER function that is used for drawing scrollbar steppers,

Sun Apr 21 14:10:04 2002  Owen Taylor  <otaylor@redhat.com>

        * pixbuf-rc-style.c pixbuf.h pixbuf-draw.c: Add a fake STEPPER
        function that is used for drawing scrollbar steppers,
        so that themes that want to draw the button and arrow
        separately can override the default handling.

        * pixbuf-draw.c: Remove draw_polygon() since it was
        just a cut-and-paste of the default one. Remove
        some unused code.