MFC r347244:

Move contrib/zlib to sys/contrib/zlib so that we can use it in kernel.
This is a prerequisite of unifying kernel zlib instances.

Submitted by: Yoshihiro Ota <ota at j.email.ne.jp>
Approved by: re (kib)

Move contrib/zlib to sys/contrib/zlib so that we can use it in kernel.
This is a prerequisite of unifying kernel zlib instances.

Submitted by: Yoshihiro Ota <ota at j.email.ne.jp>
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D20191

MFV r311279: zlib 1.2.10.

MFC after: 1 month

Restructure libz, place vendor files in contrib/zlib like other third
party software, this provides more standarized import workflow and
makes future upgrades easier.

The following files are new with this commit:

zconf.h.in
zlib.map
zlib.pc.in

They are not connected to build, but were kept in tree for reference
for future maintenance.

All our local trivial changes were applied to contrib/zlib, and the
contrib/zlib vendor source code is intended to 100% match lib/libz
before this commit.

MFC after: 2 weeks

Copy vendor/libz@250225 to vendor/zlib.

Vendor import of zlib 1.2.8.

Vendor import of zlib 1.2.7.

Vendor import of zlib 1.2.6.

Vendor import of zlib 1.2.4 (trimmed).

Flattern zlib vendor tree.

Vendor import of ZLib 1.2.3.

ZLib 1.2.2

Import zlib 1.2.1 (trimmed)

Import zlib 1.1.4 onto the vendor branch.

Initial import of zlib-1.1.1

PR: 5869
Reviewed by: jdp

Initial import of zlib-1.0.4