gfx: circle: Speed up.
gfx: circle: Speed up.

Speed up the case where circle is not clipped by 15-20% by having a
special case where when the whole circle is in the pixmap.

Signed-off-by: Cyril Hrubis <b1e90efd3b808b8e0bcf2a9a55fd8b9a779bfd81@ucw.cz>

gfxprim/gfxprim,gfxprim/gfxprim,gfxprim/gfxprim,gfxprim/gfxprim,gfxprim/gfxprim