oraclejdk8: Fix installation of JCE

Oracle changed the path of the files.

Previous versions looked like:

    $ jar tf UnlimitedJCEPolicyJDK7.zip
    UnlimitedJCEPolicy/
    UnlimitedJCEPolicy/US_export_policy.jar
    UnlimitedJCEPolicy/local_policy.jar
    UnlimitedJCEPolicy/README.txt

The new version looks like:

    $ jar tf jce_policy-8.zip
    UnlimitedJCEPolicyJDK8/
    UnlimitedJCEPolicyJDK8/local_policy.jar
    UnlimitedJCEPolicyJDK8/README.txt
    UnlimitedJCEPolicyJDK8/US_export_policy.jar

A better solution is probably just to trim the directory off completely.