Review request: JDK-8043277: Update jdk regression tests to extend the default security policy instead of override

[Mandy Chung]

jtreg policy option overrides the system security policy file and hence
some existing test policy files have to duplicate the entries to grant
permissions for JDK.

jtreg has been enhanced to provide "java.security.policy" option to
specify using the specified policy file in the same way as
-Djava.security.policy=<policy file> to extend the system security
policy.   The current jtreg "policy" option actually translates
to -Djava.security.policy==<policy file> (double equals) to
override the system security policy.

This patch updates several tests to use the new java.security.policy
options along with removing the duplicated entries from the test policy files.

Webrev:
   http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8043277/webrev.00/

thanks
Mandy
[1] https://bugs.openjdk.java.net/browse/CODETOOLS-7900898