upload-pack: move {want,have}_obj to upload_pack_data

upload-pack: move {want,have}_obj to upload_pack_data

As we cleanup 'upload-pack.c' by using 'struct upload_pack_data'
more thoroughly, let's move the want_obj and have_obj object
arrays into 'struct upload_pack_data'.

These object arrays are used by both upload_pack() and
upload_pack_v2(), for example when these functions call
create_pack_file(). We are going to use
'struct upload_pack_data' in upload_pack() in a followup
commit.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>