The quorum driver is always built in, but it is disabled during
run-time if there's no SHA256 support available (see commit e94867ed).

This patch skips the quorum test in iotest 139 in that case.
Signed-off-by: NAlberto Garcia <berto@igalia.com>
Message-id: 1447172891-20410-1-git-send-email-berto@igalia.com
Signed-off-by: NMax Reitz <mreitz@redhat.com>