review: Add xpatch argfile creation script

[David Hill]

JBS: https://bugs.openjdk.java.net/browse/JDK-8162872

This adds a simple script that will create a "xpatch" file for a modular build output. This xpatch file will resemble the current build/xpatch.args file created by the build.

This script is needed if you want to copy/download or whatever the build output to another location. The arguments in the file really have to be full paths to enable Java to find them.

Script is attached to the JBS.

-- 
David Hill<David.Hill at Oracle.com>
Java Embedded Development

"A man's feet should be planted in his country, but his eyes should survey the world."
-- George Santayana (1863 - 1952)