[clang] [analyzer] Remove some false negatives in StackAddrEscapeChecker (PR #125638)

[Michael Flanders via cfe-commits]

Flandini wrote:

> I think this is going in the right direction but I'd love to see more tests and some more thought about some scenarios.

I'll do some structural induction approach to what could be returned and what could hold which things, and make sure these all have some test case coverage.

https://github.com/llvm/llvm-project/pull/125638