Move the setting of oi->whence to sha1_loose_object_info() and
packed_object_info().
This allows sha1_object_info_extended() to not need to know about the
delta base cache. This will be useful during a future refactoring in
which packfile-related functions, including the handling of the delta
base cache, will be moved to a separate file.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>