[12] RFR 8210695: Create test to cover JDK-8205330 InitialDirContext ctor sometimes throws NPE if the server has sent a disconnection

[Chris Yin]

Please have a review for below new added test to cover JDK-8205330, thanks

This test used dummy ldap server to simulate the scenario to send “Notice of Disconnection” after binding, it will repeat InitialDirContext() for 1000 times (normally the NPE bug should be hit less than 100 times run, but just in case), test failed with NPE if without JDK-8205330 fix change and passed after the fix.

I put this test under test/jdk/com/sun/jndi/ldap/ since the bug root cause is from com.sun.jndi.ldap.LdapClient, feel free to let me know if it should be moved to other suitable folder.

bug: https://bugs.openjdk.java.net/browse/JDK-8210695
webrev: http://cr.openjdk.java.net/~xyin/8210695/webrev.00/

Regards,
Chris