adding rsockets support into JDK

[Alan Bateman]

Lucy,

I checked the CSR and it looks good but in the class description it has 
the wording that we discussed in mail:

"The selector provider does not support datagram channels and pipes. The 
The openDatagramChannel and openPipe methods throw UOE."

I assume you meant to change "UOE" to "UnsupportedOperationException", 
and I think we can link the openXXX methods to their javadoc.

For the implementation then it looks like RmdaPollSelectorProvider 
extends SelectorProviderImpl without overriding these openXXX methods. 
This means it will create instances of DatagramChannelImpl and PipeImpl 
associated with the RDMA provider which isn't right. It might be simpler 
to just extend SelectorProvider and that will force you to override the 
abstract methods.

While looking into that I see that the Linux version of 
RdmaPollSelectorProvider is still checking the value of os.name. It 
doesn't need to do that now and probably left over from an early iteration.

-Alan