14626 zlib: update to zlib-1.2.12
Reviewed by: Dan McDonald <danmcd@joyent.com>
Reviewed by: Klaus Ziegler <klausz@haus-gisela.de>
Approved by: Robert Mustacchi <rm@fingolfin.org>

10695 import zlib-1.2.11
Reviewed by: Gergő Doma <domag02@gmail.com>
Reviewed by: Andy Fiddaman <andy@omniosce.org>
Approved by: Richard Lowe <richlowe@richlowe.net>