RFR: 8056258: Analysis of public API does not take super classes into account

[Andreas Lundblad]

Hi compiler-dev,

Please review the fix for JDK-8056258 below.

Description:
The current approach for discovering dependencies in sjavac is to hook into Attr and Resolve (by registering subclasses of these classes in the context).
This is a bit ad-hoc and does currently not support discovery of super classes.
This patch refactors sjavac to instead scan for dependencies in the AST after attr is finished by using a TaskListener.

Link to web review:
http://cr.openjdk.java.net/~alundblad/8056258

Link to bug reports:
http://bugs.openjdk.java.net/browse/JDK-8056258

-- Andreas Lundblad