RFR:8205330 InitialDirContext ctor sometimes throws NPE if the server has sent a disconnection

[vyom tewari]

Hi All,

Please review this simple fix below
webrev: http://cr.openjdk.java.net/~vtewari/8205330/webrev0.0/index.html

bugid: https://bugs.openjdk.java.net/browse/JDK-8205330

This fix will resolve the race in LdapClient  where we are explicitly 
making "null" to LdapClient.conn.

Thanks,

Vyom