mount: fix _loopFsSpecsTimestamp global definition

The variable _loopFsSpecsTimestamp should be defined as global before
its first use within a function.

Change-Id: Id844fd830a7ed52196d3dda91664a370ea99938b
Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/32472
Reviewed-by: Ondřej Svoboda <osvoboda@redhat.com>
Reviewed-by: Nir Soffer <nsoffer@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>