RFR of JDK-8030175: java/rmi/registry/altSecurityManager/AltSecurityManager.java fails due to timeout

[Hamlin Li]

Would you please review the below patches?

bug: https://bugs.openjdk.java.net/browse/JDK-8030175
webrev (version A): http://cr.openjdk.java.net/~mli/8030175/webrev.00/
webrev (version B): 
http://cr.openjdk.java.net/~mli/8030175/webrev.sun.rmi.registry.RegistryImpl.00/ 


There are 2 versions to be reviewed.

In version A, just use RegistryRunner to replace rmiregistry.
In version B, refactor sun.rmi.registry.RegistryImpl to improve the 
testability of RMI code, and create/use RMIRegistryRunner to simulate 
rmiregistry.

Thank you
-Hamlin