[util] modify makeOfficialGlyphOrder func
[util] modify makeOfficialGlyphOrder func

as suggested by Adrien in https://github.com/googlei18n/ufo2ft/pull/178#discussion_r152794156

jamesgk/ufo2ft,moyogo/ufo2ft,googlefonts/ufo2ft,googlei18n/ufo2ft,jamesgk/ufo2fdk