[9] RFR JDK-8141616: Add new methods to the java Whitebox API

[Konstantin Shefov]

Hello

Please review some new methods added to the sun.hotspot.WhiteBox API.
These methods are needed to test JVMCI CompilerToVM methods, see 
https://bugs.openjdk.java.net/browse/JDK-8138708 for more info.


Bug: https://bugs.openjdk.java.net/browse/JDK-8141616
Webrev for java part: 
http://cr.openjdk.java.net/~kshefov/8141616/root/webrev.00/
Webrev for native part: 
http://cr.openjdk.java.net/~kshefov/8141616/hotspot/webrev.00/

Thanks
-Konstantin