download_zlib: pick latest version automatically (#62)

Also switch to the canonical domain name.

Author: vszakats

scripts/download_zlib.sh

@@ -3,8 +3,8 @@
 # If any commands fail, fail the script immediately.
 set -ex
 
-wget https://www.zlib.net/zlib-1.2.12.tar.gz -O /tmp/zlib-1.2.12.tar.gz
-tar -xvf /tmp/zlib-1.2.12.tar.gz --directory /tmp
+wget https://zlib.net/zlib.tar.gz -O /tmp/src.tar.gz
+tar -xvf /tmp/src.tar.gz --directory /tmp
 
-# Copy the directory into the correct place
-mv -v /tmp/zlib-1.2.12 $1
+# Move the directory into the correct place
+mv -v /tmp/zlib-* "$1"