[jdk9] RFR: 8163896: Finalizing one key of a KeyPair invalidates the other key

[Ivan Gerasimov]

Hello!

It was noticed, that SunMSCAPI implementation of a KeyPair has a 
problem: The public and the private keys share the same native handles.

As the result, when one of the keys is finalized, and its resources are 
freed, the second key becomes invalid.

Would you please help review the fix?

BUGURL: https://bugs.openjdk.java.net/browse/JDK-8163896
WEBREV: http://cr.openjdk.java.net/~igerasim/8163896/00/webrev/

With kind regards,
Ivan