jtreg 4.2-b14

[Jonathan Gibbons]

Some of you may have noticed that a new version of jtreg is available 
(jtreg4.2-b14) and is now being required in various JDK test suites.

There are two note-worthy features in this update.

 1. Action tags (like `@compile` or `@run main`) now support variable
    substitution in command arguments, using the syntax `${name}`. The
    set of names is the same as that for the `@requires` tag.  The
    feature is enabled by default for test suites that specify the use
    of jtreg4.2-b14 or later.

 2. Support is now available for using Windows Subsystem for Linux (WSL)
    as an alternative to Cygwin to run shell tests on Windows 10. This
    complements the recent new ability to build OpenJDK using WSL. Note
    that shell tests will also need to be updated in order to use this
    feature: a discussion of the issues and some recommendations have
    been posted on the OpenJDK website:
    https://openjdk.java.net/jtreg/shellTests.html

Many of the updates have been changes to the documentation, such as the 
jtreg FAQ:
https://openjdk.java.net/jtreg/faq.html

A full list of changes can be found here:
http://hg.openjdk.java.net/code-tools/jtreg/search/?rev=%22jtreg4.2-b13%22%3A%22jtreg4.2-b14%22&revcount=80

-- Jon