[8u] RFR 8062947: Fix exception message to correctly represent LDAP connection failure

[Zhengyu Gu]

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> Please post a webrev just containing this fix.

Updated: http://cr.openjdk.java.net/~zgu/JDK-8062947-8u/webrev.01/

Thanks,

-Zhengyu

> 
> Thanks,
>