This patch introduces a new Javac plugin as a build tool, written by Jan
Lahoda. The plugin creates a hash of the public API of what is being
compiled and puts it in a file. The file is only updated if there is a
difference compared to the current contents of the file. I have provided
the integration with the build system.
The benefit of this is that we finally get some reasonable incremental
build performance between modules. If you make a change to a class in
java.base that doesn't touch the public API, the build will no longer
recompile all other modules.
Webrev: http://cr.openjdk.java.net/~erikj/8182285/webrev.02/
Bug: https://bugs.openjdk.java.net/browse/JDK-8182285
/Erik
