r4242: added support for storing xattrs in a tdb. This allows all advanced NT

r4242: added support for storing xattrs in a tdb. This allows all advanced NT
attributes (streams, EAs, NT ACLs, timestamps etc) to be used on
filesystems that don't support xattrs. It also allows for large
streams, although they are very inefficient.

I won't enable this by default, as I really wrote it as a way of
testing large stream support while still using ext3, but perhaps with
a bit more work this could be generally usable.

To enable this use:

   posix:eadb = /home/test/myeas.tdb
(This used to be commit 0c927d912cb65754351189d3a0442004a14aa5c6)