test/closed/sun/net/ftp/FtpTest.java doesn't clean-up

At the end of a test run, this thread is still running. This thread should terminate or else the test should be tagged to run in othervm mode.

"Thread-547" #891 daemon prio=5 os_prio=0 tid=0x26183400 nid=0x2294 runnable [0x2795f000]
   java.lang.Thread.State: RUNNABLE
at java.net.DualStackPlainSocketImpl.accept0(Native Method)
at java.net.DualStackPlainSocketImpl.socketAccept(DualStackPlainSocketImpl.java:121)
at java.net.AbstractPlainSocketImpl.accept(AbstractPlainSocketImpl.java:404)
at java.net.PlainSocketImpl.accept(PlainSocketImpl.java:183)
- locked <0x100f6cc8> (a java.net.SocksSocketImpl)
at java.net.ServerSocket.implAccept(ServerSocket.java:521)
at java.net.ServerSocket.accept(ServerSocket.java:489)
at FtpTest$FtpServer.run(FtpTest.java:473)