First cut at splitting the backend functionality into "critcl::cc".
Incomplete. Have to handle access to "critcl::ccconfig" functionality.
Still to move collection of C sources, general data completion into "critcl::cdefs".
Still to split the BuildDefines backend out of frontend code.
Interacts with multiple variants-to-be of "cbuild" (testing for cached shlib required vs not, keeping of results vs not, loading vs not).