[clang] [StaticAnalyzer] early return if sym is concrete on assuming (PR #115579)

[Donát Nagy via cfe-commits]

https://github.com/NagyDonat commented:

Thanks for the commit, I'm satisfied with it :)

I actually like that these two related changes (the checker change and the constraint manager improvement) are handled together in a single commit -- this way somebody who browses the commit log can directly see the "other half" of the change (without following cumbersome links through "this commit is mentioned in the commit message of that one" or opening this github review).

https://github.com/llvm/llvm-project/pull/115579