[Nestmates] RFR (S): 8194906: [Nestmates] Finalize javac and other tool changes

[David Holmes]

In preparation for putting out the mainline RFR for nestmates I've made 
a few updates to the javac support as Maurizio and I have discussed 
(generally) in email in the past:

webrev: http://cr.openjdk.java.net/~dholmes/8194906/webrev/

Changes:

- move test location
- remove disableAccessors/disablePrivateAccessors flags and rely on 
nestmate support for disabling private accessors
- add disableProtectedAccessors as an experimental flag
- remove virtualizePrivateAccess flag
- add disableVirtualizedPrivateInvoke flag

The disableVirtualizedPrivateInvoke flag allows us to easily switch back 
to issuing invokeSpecial instead of invokeVirtual/invokeInterface for 
private method invocations. This can be useful for running tests in a 
"legacy" mode without having to disable all nestmate support (by running 
with --release 10 for example).

Thanks,
David