Re: [9front] move zlib source from ghostscript to ape/lib/z and update to latest zlib

[ori@eigenstate.org]

> there was a program in comp.sources.unix (or maybe misc) called unifdef which would apply selective conditionals and oreserved comments. it is so old it is orobably pre andi and may not know about c++ style comments, but maybe it would help. 
> 
> itwould allow you tokeep only the os support you need - and make the code mire readable perhaps.
> 

On one hand, yes -- unifdef will let you do that.  On the other hand,
unless we make a considered choice to fork fully and actually
*maintain* a forked version of the initial code, I think it's better
to keep the sources of ported code as close to upstream as possible,
so that it's easy to import new versions and update it -- and submit
portabillity fixes to the maintainers, so we don't have to move them
along manually to new versions.

In general, plan 9 ports have the problem of being off-brand tarballs
that, to a good approximation, never get updated.

I think it's worth trying to change that situation, so we actually
maintain the things we decide are worth porting.