Function leveldb_comparator_create

pub unsafe extern "C" fn leveldb_comparator_create(
    state: *mut c_void,
    destructor: extern "C" fn(*mut c_void),
    compare: extern "C" fn(*mut c_void, *const c_char, size_t, *const c_char, size_t) -> c_int,
    name: extern "C" fn(*mut c_void) -> *const c_char,
) -> *mut leveldb_comparator_t