[9] RFR: 8140470: javax/xml/crypto/dsig/SecurityManager/XMLDSigWithSecMgr.java failed with java.security.AccessControlException

[Artem Smotrakov]

Hello,

Please review this small fix which updates XMLDSigWithSecMgr.java test 
to extend the default security policy instead of override. Please see 
details here:

https://bugs.openjdk.java.net/browse/JDK-8140470?focusedCommentId=13873347&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13873347

The test could use "@run main/othervm/java.security.policy" action, but 
sometimes it may be better to enable a security manager during test 
execution to avoid granting many additional permissions if a test 
requires some setup. I tried to set "java.security.policy" system 
property just before enabling a security manager, and it seems to work fine.

Bug: https://bugs.openjdk.java.net/browse/JDK-8140470
Webrev: http://cr.openjdk.java.net/~asmotrak/8140470/webrev.00/

Artem