RFR: JDK-8217335: Add a script to generate --release data

[Jan Lahoda]

Hi,

As suggested here:
https://mail.openjdk.java.net/pipermail/compiler-dev/2019-January/012876.html

This is a separate patch that adds a script to generate --release N data.

Webrev: http://cr.openjdk.java.net/~jlahoda/8217335/webrev.00/
JBS: https://bugs.openjdk.java.net/browse/JDK-8217335

Jan