pack-redundant: type cleanups.

pack-redundant: type cleanups.

Binary representation of object names are unsigned char[20], not
signed.  Also verbose output had %lu format printing size_t
without (unsigned long) cast other places already had, so match
that.  Using format %zu was suggested but might not be supported
as widely.

Noted by Morten Welinder, fixed with input from H. Peter Anvin
and Hideaki Yoshifuji.

Signed-off-by: Junio C Hamano <junkio@cox.net>