RFR 8026946: JvmtiEnv::SetBreakpoint and JvmtiEnv::ClearBreakpoint should use MethodH,andle

[Coleen Phillimore]

8026948: JvmtiEnv::SetBreakpoint and JvmtiEnv::ClearBreakpoint might not 
work with anonymous classes
Summary: Walk methods in breakpoints for marking on stack so they aren't 
deallocated by redefine classes.  Use class_holder rather than 
class_loader to keep GC from reclaiming class owning the method.

This is two bug fixes to the same code.

open webrev at http://cr.openjdk.java.net/~coleenp/8026946_8026948/
bug link https://bugs.openjdk.java.net/browse/JDK-8026946
                https://bugs.openjdk.java.net/browse/JDK-8026948

Tested with vm.quick.testlist - and verified the jdi tests eg 
nsk/jdi/BScenarios/hotswap/tc01x001 test this path.

Thanks,
Coleen