lib/repo-pull: Fix counting of latest commits when finding repos

lib/repo-pull: Fix counting of latest commits when finding repos

The intended behaviour of ostree_repo_find_remotes() is to return
results which have the latest version of at least one of the requested
refs. Results which have some of the requested refs, but don’t have the
latest version of any of them, should be ignored. The logic to do this
was broken in the case that a result contained a positive number of the
requested refs, but none of them were the latest version. (It previously
worked when the result contained none of the requested refs.)

Fix the counting to work correctly in both cases.

Signed-off-by: Philip Withnall <withnall@endlessm.com>
Closes: #1058
Approved by: cgwalters