proposal: merge waf build of s4 to master

[tridge at samba.org]

Hi Simo,

Assuming the waf build goes into master, would you have any objections
to me switching ldb in the build farm over to using a waf based build?

ldb hasn't built correctly in the build farm for over a year now, as
we never got the library dependencies right in the farm.

I've setup 'waf dist' for ldb so that it produces a distribution
tarball that includes all the dependent libraries, which means it
builds fine with the waf build. I think using ldb as a test for this
in the build farm would be a good idea as the current ldb builds in
the farm are not in any way useful.

We should probably also switch over tdb at some point, as currently it
builds the tdb test suite against the system version of tdb if it
exists. This means tdb is not getting valid testing in the build farm.

Cheers, Tridge