RFR: JDK-8231910: Expose the APPDIR variable to applications that use jpackage

[Andy Herrick]

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).

This change is to Expose the macro $APPDIR for use in --java-options 
value, to rename macros to mean what they are called, and to eliminate 
several unused macros.

[1] https://bugs.openjdk.java.net/browse/JDK-8231910

[2] http://cr.openjdk.java.net/~herrick/8231910/

/Andy