package: ignore more metadata files

Add a minor optimization, as well, since we must call this for every
file in the package.
filecache: plug FD leak

With a large enough pool dir, I ran out of file descriptors.
repose: fix typo in error message
buildsys: always compile with debug file

You can always strip these out afterwards, but you can never readd
them. No need to force people to add this themselves.