Apache Calcite: Migrate git mirrors

Please migrate github mirror from http://github.com/apache/incubator-calcite to http://github.com/apache/calcite

In the top-left corner of https://github.com/apache/calcite/, check that its description is "Mirror of Apache Calcite: A dynamic data management framework" and source is "mirrored from git://git.apache.org/calcite.git". (There should be no references to "Optiq".)