#include <fontconfig/fontconfig.h>
FcLangResult FcLangSetCompare (const FcLangSet *ls_a, const FcLangSet *ls_b);
FcLangSetCompare compares language coverage for ls_a and ls_b. If they share any language and territory pair, this function returns FcLangEqual. If they share a language but differ in which territory that language is for, this function returns FcLangDifferentTerritory. If they share no languages in common, this function returns FcLangDifferentLang.