RFR 8065076/9, test/java/net/SocketPermission/SocketPermissionTest.java failed intermittently

[Felix Yang]

Hi all,
     please review the fix for 
test/java/net/SocketPermission/SocketPermissionTest.java, which fails 
frequently with "java.net.BindException: Address already in use".

Bug: https://bugs.openjdk.java.net/browse/JDK-8065076
Webrev: http://cr.openjdk.java.net/~xiaofeya/8065076/webrev.00

The test uses getFreePort() test util library to verify permission on 
specific "host:port".  This fix added retries to avoid possible binding 
failures:
1. A port may be still occupied for a short moment after socket close.
2. Another application is possible to occupy the same port during the 
short time window of open-close-reuse. This has been observed in 
experimental test runs.

Thanks,
Felix