Bring back '#include <lib/libz/zlib.h>', but inside #ifdev GPT. GPT routines use crc32().
Bring back '#include <lib/libz/zlib.h>', but inside #ifdev GPT. GPT
routines use crc32().

ok jsg@ doug@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars