RFR: JDK-8226532: cleanup is not called when jpackage command fails.

[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).

Trivial fix to clean up the temp directory created by jpackage.

[1] https://bugs.openjdk.java.net/browse/JDK-8226532

[2] http://cr.openjdk.java.net/~herrick/8226532/

/Andy