6961630: TEST_BUG: Several SocketChannel and Selector tests can fail with "address already in use"

[Alan Bateman]

Chris - do you mind looking at yet another webrev to address further 
intermittent failures. It's mostly older Selector and SocketChannel 
tests using fixed ports. Also one SelectorProvider test uses a small 
timeout causing it to fail periodically when the machine is loaded.  The 
webrev is here:
    http://cr.openjdk.java.net/~alanb/6961630/webrev/

Thanks,
Alan.