wcsncasecmp
extern int wcsncasecmp(const wchar_t *wcs1, const wchar_t *wcs2,
B_DEFINE_WEAK_ALIAS(__wcsncasecmp, wcsncasecmp);
int result = sign(wcsncasecmp(a, b, 0));
int result = sign(wcsncasecmp(a, b, 4));
int result = sign(wcsncasecmp(a, b, 5));
int result = sign(wcsncasecmp(a, b, (size_t)-1));