mds: include advisory `path` field in damage

mds: include advisory `path` field in damage

This will just be whatever path we were looking
at at the point that damage was notified -- no
intention whatsoever of providing any up to date
path or resolution when there are multiple paths
to an inode.

Fixes: http://tracker.ceph.com/issues/18509
Signed-off-by: John Spray <john.spray@redhat.com>
(cherry picked from commit c0bff51ef409eb6e4b2fc248e06e5a7e43faf51e)

Conflicts:
    src/mds/CDir.cc - omit dout(10) because jewel does not have cb86740a
    src/mds/ScrubStack.cc - jewel does not have 7b456109 which changed
       in->make_path_string_projected() call to in->make_path_string() but
       it's moot because that line is dropped