Updating waf to 1.6

[Kevin Kofler]

Toshio Kuratomi wrote:
> It's possible that it could be shown to be a copylib:
> https://fedoraproject.org/wiki/Packaging:No_Bundled_Libraries#Copylibs

That whole CONCEPT of a "copylib" is broken and it's sad that we're making 
exceptions for those.

> But waf does make periodic releases so that might not be the right
> exception.  If you could draw parallels between the autotools and waf,
> that might be a way to look at it.

Actually, the right parallel to draw here is to finally start requiring 
autotools-using projects to run a full autoreconf -i -f in %prep.

Generated shell scripts are NOT source code, we should require the stuff to 
be built from its true source code just as we do for Java JARs, target 
binaries in cross-compilation tools etc.

        Kevin Kofler