RFR: JDK-8226835: Command window pops up building exe package

[Alexey Semenyuk]

Please review the jpackage fix for bug [1] at [2].

This is a fix for the JDK-8200758-branch branch of the open sandbox 
repository (jpackage).

- Eliminate unexpected console window in .exe installers on Windows 
platform.

[1] https://bugs.openjdk.java.net/browse/JDK-8226835

[2] http://cr.openjdk.java.net/~asemenyuk/8226835/webrev.00/

Thanks,
Alexey