The OLD behaviors of all policies are deprecated, but only by
documentation. Add an explicit deprecation diagnostic for some policies
to encourage projects to port away from setting policies to OLD.
Restore support for the undocumented <CONFIG>_LOCATION target property
removed by commit v3.0.0-rc1~175^2 (cmTarget: Remove support for
<CONFIG>_LOCATION property, 2013-12-30) as part of the CMP0026 OLD
behavior.