cmake: Backport -C, -D and -U option parsing fix to the 3.13 release branch

CMake 3.13 added the -S option for the cmake command. As users have started trying to use it, on multiple occasions I've seen them hit the problems that have already been fixed on master by !2517 (merged). Since 3.13 is the first release where -S was formally supported (previously it was the undocumented -H option), it makes sense to back-port this fix to the release branch (as proposed and approved in !2517 (comment 495303)).

The problem reported in #18707 (closed) is a combination of the bugs fixed by !2517 (merged) and what appear to be additional errors in the -S (and probably -B) handling. Having the changes from !2517 (merged) back-ported first will allow the remaining fixes to be merged more cleanly.