cmState: Restore renamed commands on cleanup.

Commit v3.3.0-rc1~196^2~7 (cmake: Simplify command clean up
loop., 2015-04-12) introduced a bug that built-in commands which
were renamed no longer had their original name restored when
cleanup is performed between configure runs.  Check for that
and restore the commands with their original name.

Extend the complex test for this. That test is run by ctest with
the --build-two-config command line option.