Tweak the gitarchive exclude handling not to error if excluded files
don't match.
Also return the tagname created so that other code can then use it.
(From OE-Core rev: 2df9c2248ac4996ad1fd1fe9f492eb2d71b758cb)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 1adba3430faffdf6217b6a00533a3b48a9388abc)
Signed-off-by: Steve Sakoman <steve@sakoman.com>