check_everything_connected: always pass --quiet to rev-list

check_everything_connected: always pass --quiet to rev-list

The check_everything_connected function takes a "quiet"
parameter which does two things if non-zero:

  1. redirect rev-list's stderr to /dev/null to avoid
     showing errors to the user

  2. pass "--quiet" to rev-list

Item (1) is obviously useful. But item (2) is
surprisingly not. For rev-list, "--quiet" does not have
anything to do with chattiness on stderr; it tells rev-list
not to bother writing the list of traversed objects to
stdout, for efficiency.  And since we always redirect
rev-list's stdout to /dev/null in this function, there is no
point in asking it to ever write anything to stdout.

The efficiency gains are modest; a best-of-five run of "git
rev-list --objects --all" on linux.git dropped from 32.013s
to 30.502s when adding "--quiet". That's only about 5%, but
given how easy it is, it's worth doing.

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