[9] request for review 8062548: Support duplicate Extended Key Usage certificate extensions

[Vincent Ryan]

Please review this fix that adds support for X.509 certificates that contain more than one Extended Key Usage extension.
The certificate parser now merges duplicate EKU objects into a single one.

Webrev: http://cr.openjdk.java.net/~vinnie/8062548/webrev.00/
Bug: https://bugs.openjdk.java.net/browse/JDK-8062548

Thanks.