mds: allow for old fs's with stray instead of stray0
mds: allow for old fs's with stray instead of stray0

New fs's get stray0, but we want to still behave with old ones.

Signed-off-by: Sage Weil <6dd34506bbd5e58221bbb3e4732d97c91f02277b@newdream.net>

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph