Status.hs: don't leak halfopen files

Leaked descriptors are seen as:
    $ ulimit -n 100
    $ hackport status --to-portage
    hackport: dev-haskell/cabal/cabal-1.16.0.3.ebuild: openFile: resource exhausted (Too many open files)

Patch uses strict bytestring for open-read-and-close.

Found by gienah.

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>