Add script so that output is verifiable

Author: vmchale

update-c-sources.sh

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+
+set -e pipefail
+
+zlib="$(curl http://zlib.net/ | rg '(zlib-\d+(\.\d+)*)\.tar\.gz' -o -r '$1' | head -n1)"
+
+curl "http://zlib.net/${zlib}.tar.gz" -o "${zlib}.tar.gz"
+tar xvf "${zlib}.tar.gz"
+
+for csrc in $(ls -1 cbits)
+do
+    cp "${zlib}/${csrc}" cbits/
+done