RFR [XS] 8155239 [TESTBUG] Simple test setup for JVMTI ClassFileLoadHook

[Ioi Lam]

Hi,

Please review this simple test bug:

https://bugs.openjdk.java.net/browse/JDK-8155239
http://cr.openjdk.java.net/~iklam/jdk9/8155239_simple_classfileloadhook.v01/

Testing ClassFileLoadHook is a pain. In many cases, we are not testing 
CFLH itself, but rather "how does my feature interact with CFLH. One 
example is the interaction between CDS and CFLH. This RFE makes it easy 
to write such tests.

Please see SimpleClassFileLoadHookTest.java for an example.

I've tested under Linux and I am now trying to test under all other 
platforms.

Thanks
- Ioi