[clang] [clang] Expose CrossTU context in CheckerContext.h (PR #181713)

[Balázs Benics via cfe-commits]

steakhal wrote:

> The SSAF suggested by steakhal is also important to mention, especially since you only want AST-based analysis and not path-sensitive analysis. (However, I'm not too familiar with that tool.)

Our team is working hard on upstreaming this framework every week (this week included) and parts are already there, but the bulk of it is till missing or yet to be designed and then upstreamed; but the goal is clear: have a truly scalable cross translation unit analysis that scales to large applications and fits into existing build infrastructures.

https://github.com/llvm/llvm-project/pull/181713