8180904: Hotspot tests running with -agentvm failing due to classpath
Add -cp System.getProperty("java.class.path") to ProcessBuilder arguments.
Reviewed-by: sla, gtriantafill
Modify WhiteBoxAPI to use interface classes from test/testlibrary instead, add ClassFileInstaller to resolve the boot class path issue
Reviewed-by: ctornqvi, dsamersoff, coleenp, kvn