RFR 8081390, javax/management/remote/mandatory/connection/RMIConnector_NPETest.java may leave orphaned processes

[Felix Yang]

Hi,

   please review the small fix to avoid  orphaned processes left.

Bug:

    https://bugs.openjdk.java.net/browse/JDK-8081390

Webrev:

    http://cr.openjdk.java.net/~xiaofeya/8081390/webrev.00/

Thanks,

Felix