Function libc::qsort_r

pub unsafe extern "C" fn qsort_r(
    base: *mut c_void, 
    num: size_t, 
    size: size_t, 
    compar: Option<unsafe extern "C" fn(_: *const c_void, _: *const c_void, _: *mut c_void) -> c_int>, 
    arg: *mut c_void
)