zlib: add script to import zlib 1.2.3 from upstream
CMake has vendored this version for a long time.
Import it using our modern approach.
diff --git a/Utilities/Scripts/update-zlib.bash b/Utilities/Scripts/update-zlib.bash
new file mode 100755
index 0000000..2c45184
--- /dev/null
+++ b/Utilities/Scripts/update-zlib.bash
@@ -0,0 +1,51 @@
+#!/usr/bin/env bash
+
+set -e
+set -x
+shopt -s dotglob
+
+readonly name="zlib"
+readonly ownership="zlib upstream <kwrobot@kitware.com>"
+readonly subtree="Utilities/cmzlib"
+readonly repo="https://github.com/madler/zlib.git"
+readonly tag="v1.2.3"
+readonly shortlog=false
+readonly paths="
+ README
+
+ adler32.c
+ compress.c
+ crc32.c
+ crc32.h
+ deflate.c
+ deflate.h
+ gzio.c
+ inffast.c
+ inffast.h
+ inffixed.h
+ inflate.c
+ inflate.h
+ inftrees.c
+ inftrees.h
+ trees.c
+ trees.h
+ uncompr.c
+ zconf.h
+ zlib.h
+ zutil.c
+ zutil.h
+"
+
+extract_source () {
+ git_archive
+ pushd "${extractdir}/${name}-reduced"
+ echo "* -whitespace" > .gitattributes
+ echo -n "'zlib' general purpose compression library
+version 1.2.3, July 18th, 2005
+
+Copyright " > Copyright.txt
+ sed -n '/^ (C) 1995-/,+19 {s/^ \?//;s/2004/2005/;p}' README >> Copyright.txt
+ popd
+}
+
+. "${BASH_SOURCE%/*}/update-third-party.bash"
