8199329: Remove code that attempts to read bytes after connection reset reported

[Alan Bateman]

Classic networking has some curious code to deal with connection resets. 
I needed to dig into ancient history to find the issues and original 
motivations.

When a connection reset is reported (usually ECONNRESET) then further 
attempts to read from the socket will typically return -1 (EOF). Classic 
networking papers over this so that further attempts with the socket 
APIs to read bytes will continue to throw SocketException "connection 
reset". Furthermore, it allows for cases where the platform can read 
bytes from the socket buffer after ECONNRESET has been reported. None of 
the main stream platforms do this and it's hard to imagine anything 
depending on such unpredictable behavior. I'm running into this odd code 
as part of cleanup to the read/write code paths and reducing them down 
to a single blocking call.

I would like to remove the legacy/undocumented behavior that attempts to 
read beyond the connection reset. The code to consistently throw 
IOException once ECONNRESET is returned is retained as it's possible 
that code relies on this.

The proposed changes are here:
    http://cr.openjdk.java.net/~alanb/8199329/webrev/

All existing tests pass with these changes.

-Alan