RFR: JDK-8251988: jpackage --runtime-image fails on mac when using JDK11 based runtime.

[Andy Herrick]

Please review the jpackage fix at [1] to issue [2].

This fixes the problem loading libjli.dylib as well as  providing some 
useful generic system properties.

/Andy


[1] - http://cr.openjdk.java.net/~herrick/8251988/webrev.02/ 
<http://cr.openjdk.java.net/~herrick/8251988/webrev.01/>

[2] - https://bugs.openjdk.java.net/browse/JDK-8251988