Don't remove overlaps from empty or all-component glyphs
Don't remove overlaps from empty or all-component glyphs

or else with pyclipper 1.1.0 we get a pyclipper.ClipperException:
See https://github.com/greginvm/pyclipper/pull/14

googlefonts/fontmake,googlefonts/fontmake,googlei18n/fontmake,googlei18n/fontmake