accelerated zlib experiment

[René J.V. Bertin]

As announced in the earlier thread, I've created a +cloudflare variant for port:zlib that provides faster compression on recent enough Intel CPUs (SSE4 is required, which is probably the case on all Intel Macs.

Applying these patches may change the applicable license, though it seems that I excluded the only file that is (almost) explicitly GPL and that's not part of stock zlib. I'm waiting on clarification about the changes CloudFlare made to existing zlib code.

The resulting binary *is* a drop-in replacement for the stock 1.2.8 zlib library.

https://github.com/RJVB/mp-port-repository/tree/master/archivers/zlib

You'll also need
https://github.com/RJVB/mp-port-repository/tree/master/sysutils/cpuid

I've seen compression time decrease by up to 55% with level 7 thanks to this patch.

R.