jpackage: support for environment variables in --java-options

[Serban Iordache]

Hi,

Is there a way to pass values from environment variables when using
--java-options?

It would be nice to be able to write something like this:
--java-options "-DmyAppData=$HOME/.myData"

(Instead of using the $ sign, another notation may be more appropriate, in
order to not conflict with macros such as $APPDIR or $ROOTDIR.)

- Serban