Convert struct delta_info and struct object_info, as well as the various
functions, to use struct object_id. Convert several hard-coded 20
values to GIT_SHA1_RAWSZ. Among the functions converted is a caller of
lookup_blob, which we will convert shortly.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>