This is second step in the effort to unify duplicate test libraries in jdk8 into single shared test library (as in newer jdks). Motivation is to remove code duplication and make backporting simpler. It only affects tests. More details in JDK-8305329.

This changeset eliminates duplicate test lib in hotspot ( hotspot/test/testlibrary ) by unifying it with shared test library ( test/lib ). Hotspot tests have been updated to use (unified) shared test library.