Using the new Java class analyzer API, scan the bound packages
for references to Java classes and interfaces and generate Go
wrappers for them.
This is the second part of the implementation of proposal golang/go#16876.
For golang/go#16876
Change-Id: I59ec0ebdae0081a615dc34d450f344c20c03f871
Reviewed-on: https://go-review.googlesource.com/28596
Reviewed-by: David Crawshaw <crawshaw@golang.org>