Unmodified sources for zlib-1.2.5 have been included with Mono, this
is used to support compression and uncompression in older Linux
systems that might have shipped older versions of zlib and to reduce
dependencies.

They were imported in Oct 22 2010.

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Updated to 1.2.11 July 2019
Sources of truth:
	https://packages.ubuntu.com/disco/zlib1g (or newer, but you get the idea)
	https://packages.debian.org/stretch/zlib1g-dev (or newer, but you get the idea)
	https://github.com/madler/zlib/tree/master
	https://github.com/madler/zlib/tree/develop
	mono commit b5a0b8e0a8bb2fe790dc2f34a1a846f8efc470db (57ea99c5011aa2d9ce2be308041aafe76a469e5c)
	Possibly other mono commits.

Debian matches master
Ubuntu 1804 has one commit from devel and one extra function for compat.