Removal of zlib, take 2.

[Ira Cooper]

Code for review is at:
http://git.samba.org/?p=ira/wip.git;a=shortlog;h=refs/heads/zlib_removal

This is the "remove zlib, and break all systems without zlib" version.

I copied the configure check used previously, so it should detect libraries
the exact same way we do today, just to avoid any issues with botching the
check.

Regarding making zlib truly optional:  I've made good progress on this
front, but the patch is substantially more complex, because I didn't fully
listen to Volker ;).  I also conditionalized zlib in the AD DC.  It looks
"plausible" that it should work, but I don't know the right tests to run,
nor have a test environment of that type setup.  So I'd like some
assistance in getting those patches properly tested.

I plan to follow up today's submission with similar patches for iniparser,
and popt.

Thanks,

-Ira