git-p4: don't exclude other files with same prefix

git-p4: don't exclude other files with same prefix

Make sure not to exclude files unintentionally
if exclude paths are specified without a trailing /.
I.e., don't exclude "//depot/file_dont_exclude" if run with "-//depot/file".

Do this by ensuring that paths without a trailing "/" are only matched completely.

Also, abort path search on the first match as a micro-optimization.

Signed-off-by: Andrey Mazo <amazo@checkvideo.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>