upload-pack: use repository struct to get config

upload-pack: use repository struct to get config

Our upload_pack_v2() function gets a repository struct, but we ignore it
totally.  In practice this doesn't cause any problems, as it will never
differ from the_repository. But in the spirit of taking a small step
towards getting rid of the_repository, let's at least starting using it
to grab config. There are probably other spots that could benefit, but
it's a start.

Note that we don't need to pass the repo for protected_config(); the
whole point there is that we are not looking at repo config, so there is
no repo-specific version of the function.

For the v0 version of the protocol, we're not passed a repository
struct, so we'll continue to use the_repository there.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>