8203765: java/nio/channels/Selector/SelectAndClose: add some prints and @intermittent tag

[Alan Bateman]

On 30/05/2018 21:56, Brian Burkhalter wrote:
> All suggested changes have been made [1] and tested on all platforms. 
> In addition I removed the “closed” variable and the testing of it as 
> it now seems pointless.
>
Looks good.

-Alan