regent: Formally deprecate SCR
As noted in https://github.com/StanfordLegion/legion/issues/1528, SCR is deprecated and will be removed in a future release. This change adds a warning so that users will be aware of its pending removal.
As noted in https://github.com/StanfordLegion/legion/issues/1528, SCR is deprecated and will be removed in a future release. This change adds a warning so that users will be aware of its pending removal.