RFR of JDK-8025199: java/rmi/registry/reexport/Reexport.java failed with: Port already in use

[Hamlin Li]

Would you please review the below patch?

bug: https://bugs.openjdk.java.net/browse/JDK-8025199
webrev: http://cr.openjdk.java.net/~mli/8025199/webrev.00

Root cause: running registry on TestLibrary.getUnusedRandomPort() will 
cause "port in use" exception, as there is a time window for a 
interloper to occupy the "free" port.

Solution: in RegistryRunner print out the port running registry, add a 
class REGISTRY to control and monitor the registry sub-process, and get 
the running port.


Thank you
-Hamlin