Function encoding_c::encoding_for_label_no_replacement

#[no_mangle]
pub unsafe extern fn encoding_for_label_no_replacement(label: *const u8,
                                                       label_len: usize)
                                                       -> *const Encoding

This function behaves the same as encoding_for_label(), except when encoding_for_label() would return REPLACEMENT_ENCODING, this method returns NULL instead.

This method is useful in scenarios where a fatal error is required upon invalid label, because in those cases the caller typically wishes to treat the labels that map to the replacement encoding as fatal errors, too.

Undefined behavior

UB ensues if label and label_len don't designate a valid memory block.