sha1dc: update from upstream

sha1dc: update from upstream

Update sha1dc from the latest version by the upstream
maintainer[1]. See 07a20f569b ("Makefile: fix unaligned loads in
sha1dc with UBSan", 2019-03-12) for the last update.

This fixes an issue where HP-UX IA64 was wrongly detected as a
Little-endian instead of a Big-endian system, see [2] and [3].

1. https://github.com/cr-marcstevens/sha1collisiondetection/commit/855827c583bc30645ba427885caa40c5b81764d2
2. https://public-inbox.org/git/603989bd-f86d-c61d-c6f5-fb6748a65ba9@siemens.com/
3. https://github.com/cr-marcstevens/sha1collisiondetection/pull/50

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>