With 77b9b1d1 (add_to_alternates_file: don't add duplicate entries,
2015-08-10) the last caller of function "hold_lock_file_for_append"
has been removed, so we can remove the function as well.
Signed-off-by: NRalf Thielow <ralf.thielow@gmail.com>
Acked-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>