RFR: JDK-8067759 Test bundles

[Ingemar Aberg]

The ability to build (when applicable) and bundle the tests that are in 
the JDK source code at the same time as the product is built is needed. 
(JDK-8067759)

This change provides basic infra structure for creating a test image and 
bundling it in the same manner as other images/bundles

No tests are added to the image/bundle by this change. Tests can be 
added by creating a rule that puts them in the $(TEST_IMAGE_DIR) and 
having the 'test-image' make  target depend on it.

Bug: https://bugs.openjdk.java.net/browse/JDK-8067759
WebRev: http://cr.openjdk.java.net/~ehelin/ingo/8067759/webrev.01/