proposal: merge waf build of s4 to master

[tridge at samba.org]

Hi Simo,

I had a play with cross-compiling with the waf build this evening. It
turned out to be very easy. I've now successfully built cross-compiled
binaries for tdb, talloc, ldb, tevent and libreplace on my x86_64
Ubuntu box for a ARM target.

I wrote up a small howto here:

  http://wiki.samba.org/index.php/Waf#cross-compiling

The approach I took is to install both a cross-compiler and a qemu ARM
emulator. Then it runs the configure checks using qemu (which is very
fast, as it does syscall emulation). That means we get completely
correct configure checking for the target platform.

It is a bit trickier for the full s4 build, as that builds python
extensions. That means I need to install a cross-build of the python
libs in /usr/arm-linux-gnu. If I can get apt-cross working then I'll
try that, otherwise I'll just use dpkg-cross and grab the ARM debs
manually.

It is very easy for all our libs though, and I expect it will be just
as easy for s3.

Cheers, Tridge