diff_tree: disable QUICK optimization with diff filter

diff_tree: disable QUICK optimization with diff filter

We stop looking for changes early with QUICK, so our diff
queue contains only a subset of the changes. However, we
don't apply diff filters until later; it will appear at that
point as though there are no changes matching our filter,
when in reality we simply didn't keep looking for changes
long enough.

Commit 2cfe8a6 (diff --quiet: disable optimization when
--diff-filter=X is used, 2011-03-16) fixes this in some
cases by disabling the optimization when a filter is
present. However, it only tweaked run_diff_files, missing
the similar case in diff_tree. Thus the fix worked only for
diffing the working tree and index, but not between trees.

Noticed by Yasushi SHOJI.

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