Review request: JDK-8159596 Add java --dry-run

[Mandy Chung]

Webrev:
  http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8159596/webrev.00/

`java --dry-run` will create the VM, load the main, locate the static void main method, and exit (with 0) instead of executing the method.  As all module options are processed and the boot layer is created, this would be useful to sanity check the options and detect possible issues.

Mandy