fontc crashes on super bezier segments (3+ off-curve points before a curve)

fontc rejects glyphs that contain "super bezier" segments (cubic curve segments with more than 2 consecutive off-curve control points). These exist in some sources, and are supported by fontmake.

```
python3 -m ttx_diff 'https://github.com/Omnibus-Type/Barrio?8f33bf10cb#Barriecito/sources/Barriecito.glyphs'
```

fontTools handles this via `decomposeSuperBezierSegment` in [`fonttools/Lib/fontTools/pens/basePen.py:389`](https://github.com/fonttools/fonttools/blob/57fb47/Lib/fontTools/pens/basePen.py#L389-L421). When `BasePen.curveTo` receives more than 3 points (i.e. more than 2 control points), it decomposes the super bezier into multiple standard cubic bezier segments that together reproduce the same curve.