TDB2 inclusion?

[tridge at samba.org]

Hi Rusty,

 > (1) It adds a lib/ccan dir

I like the idea of putting ccan code in lib/ccan, preferably with a
README that points at ccan.ozlabs.org. I suspect we'll be pulling more
code from ccan in the future. 

 > (2) It makes requirements on tdb_ functions in the tree
 >     - Mainly, TDB2 returns a (negative) error code rather than -1.  Most
 >       places check for != 0 (which works across both), so I just made
 >       that the norm rather than wrapping everything.

this is a good API improvement. 

 > (3) It redirects all the tdb dependencies to tdb_compat
 >     - Compatibility wrappers and figuring out whether we're tdb1 or tdb2
 >       lives here, very little else should care.

ok

 > Now, I'm not committing to TDB2 stability at this stage, but integration
 > would make my life simpler (vs. continually rebasing).  The major
 > missing piece (other than debugging and tuning) is that I need to
 > implement the ability to read and write TDB1 files.
 > 
 >         git://git.samba.org/rusty/samba.git #tdb2-wip

Someone (maybe me?) needs to review this before it goes in, but I
think the idea of it going into master soon is good in principle.

Cheers, Tridge