[clang] [LifetimeSafety] Add bailout for large CFGs (PR #170444)

[Gábor Horváth via cfe-commits]

https://github.com/Xazax-hun commented:

We should be able to construct a small test where an error is not found because the analysis is skipped due to the CFG size. 

I also wonder if it is better to do something else for functions with large CFGs. E.g., instead of entirely skipping them, we could just visit all nodes ones  and not iterate to a fixed-point. 

https://github.com/llvm/llvm-project/pull/170444