Extract classes out of jarjar jar for static java libraries

jarjar modifies the .class files in a jar, when using static java
library dependencies we need to use the modified class files and
not the ones that javac produced.  If jarjar is enabled, use
the prebuilt jar extractor to get the classes out of classes-jarjar.jar
and export them through j.classJarSpecs.

Change-Id: Ia2854f1c26d630da12cab7c421007aad4f793ecd
1 file changed