fn _detect_round_segments_cjk(outline: &mut Outline, axis: &mut Axis)
Performs the additional step of detecting round segments for the CJK script group.
See https://gitlab.freedesktop.org/freetype/freetype/-/blob/57617782464411201ce7bbc93b086c1b4d7d84a5/src/autofit/afcjk.c#L818