[8] 8026301: DomainKeyStore doesn't cleanup correctly when storing to keystore

[Vincent Ryan]

Please review this fix to close output stream in DomainKeyStore:

Bug: https://bugs.openjdk.java.net/browse/JDK-8026301
Webrev: http://cr.openjdk.java.net/~vinnie/8026301/webrev.00/

Thanks.