Use latest Java release for supported version in annotation processor.

  - Fixes LOG4J2-683.
  - Since we're extending the version 6 visitor classes, we should be fine in newer Java versions (tested in Java 1.8, no problems).

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1607509 13f79535-47bb-0310-9956-ffa450edef68
Add changelog entry for LOG4J2-683.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1607510 13f79535-47bb-0310-9956-ffa450edef68