RFR of JDK-7195382: TEST_BUG: java/rmi/activation/CommandEnvironment/SetChildEnv.java can fail

[Hamlin Li]

Would you please review the below patch?

bug: https://bugs.openjdk.java.net/browse/JDK-7195382
webrev: http://cr.openjdk.java.net/~mli/7195382/webrev.00/

what's changed?
* Use createRMIDOnEphemeralPort to avoid "port in use" exception.
* Because createRMIDOnEphemeralPort will choose different ports for rmid 
for multiple runs, it will fail subsequent ActivationGroup except of 
first run, so have to run 4 test cases in different JVM by putting them 
in rather in separate "@run main/othervm".
* Put rmid.cleanup() in finally block to avoid orphan process bug.
* delete dead code.

Thank you
-Hamlin