FcLangSetHash - return a hash value for a langset
#include <fontconfig/fontconfig.h>
FcChar32 FcLangSetHash (const FcLangSet *ls);
This function returns a value which depends solely on the languages supported by
ls. Any language which equals ls will have the same result from
FcLangSetHash. However, two langsets with the same hash value may not
be equal.