Optimize Bézier bisections.

* src/raster/ftraster.c (Split_Conic, Split_Cubic): Use shifts and
refactor.
* src/smooth/ftgrays.c (gray_split_conic, gray_split_cubic): Ditto.
* src/base/ftstroke.c (ft_conic_split, ft_cubic_split): Ditto.
* src/base/ftbbox.c (cubic_peak): Use shifts.
5 files changed