RFR(S): JDK-8077137 Port jdk.internal.instrumentation to jdk 9

[Staffan Larsen]

Please review these small changes to support an addition of closed code to the 
java.instrument module.

webrev: http://cr.openjdk.java.net/~sla/8077137-open/webrev.01/ 
<http://cr.openjdk.java.net/~sla/8077137-open/webrev.01/>

Thanks,
/Staffan