RFR [7010989]: Duplicate closure of file descriptors leads to unexpected and incorrect closure of sockets

[Ivan Gerasimov]

Hello!

In the implementation of TwoStack sockets on Windows there's is a 
possibility of trying to close the sockets twice in the case of a failure.
TwoStack implementation isn't the default one, but it still can be used 
with jdk7u/8u on old platforms.

Would you please help review the fix?

BUGURL: https://bugs.openjdk.java.net/browse/JDK-7010989
WEBREV: http://cr.openjdk.java.net/~igerasim/7010989/0/webrev/

Sincerely yours,
Ivan