see https://github.com/fonttools/fonttools/blob/c3d876/Lib/fontTools/misc/classifyTools.py#L77 i.e. we want (large classes first, then lexicographic order on the glyphs); previously otlLib was sorting by the _reverse_ of (small classes first, then glyphs lexicographic order) -- effectively comparing the reverse of the glyph sets of classes of the same size. Fixes https://github.com/fonttools/fonttools/issues/3321 note the ttx dump of previously built fonts may change but there won't be any functional changes.