wip-enable-cephfs-acls

@liewegas, I already fab'ed these to the basic kernel gitbuilder for
testing.  (I had to reset your? change to kernel config).  If these
look good, I'll merge and re-fab.

(I think changing config file is a worse option in the long run,
because once it grows to more than a couple options, it'll have to be
carefully diff'ed each time we import a new config.)