mktree: do not check type of remote objects

mktree: do not check type of remote objects

With 31c8221a (mktree: validate entry type in input, 2009-05-14), we
called the sha1_object_info() API to obtain the type information, but
allowed the call to silently fail when the object was missing locally,
so that we can sanity-check the types opportunistically when the
object did exist.

The implementation is understandable because back then there was no
lazy/on-demand downloading of individual objects from the promisor
remotes that causes a long delay and materializes the object, hence
defeating the point of using "--missing".  The design is hurting us
now.

We could bypass the opportunistic type/mode consistency check
altogether when "--missing" is given, but instead, use the
oid_object_info_extended() API and tell it that we are only interested
in objects that locally exist and are immediately available by passing
OBJECT_INFO_SKIP_FETCH_OBJECT bit to it.  That way, we will still
retain the cheap and opportunistic sanity check for local objects.

Signed-off-by: Richard Oliver <roliver@roku.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>