Makefile: fix unaligned loads in sha1dc with UBSan

Makefile: fix unaligned loads in sha1dc with UBSan

The sha1dc library uses unaligned loads on platforms that support them.
This is normally what you'd want for performance, but it does cause
UBSan to complain when we compile with SANITIZE=undefined. Just like we
set -DNO_UNALIGNED_LOADS for our own code in that case, we should set
-DSHA1DC_FORCE_ALIGNED_ACCESS.

Of course that does nothing without pulling in the patches from sha1dc
to respect that define. So let's do that, too, updating both the
submodule link and our in-tree copy (from the same commit).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>