[clang] [codegen] Emit missing cleanups for stmt-expr and coro suspensions [take-2] (PR #85398)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

Instead of Expr::mayBranchOut, I'd prefer to just unconditionally create the alloca, then delete it later if it turns out we didn't actually need to emit the branch.  Trying to explicitly compute whether there's a branch out seems both difficult, and potentially costly for compile-time.

I like the unified approach here for eh and non-eh cleanups.

https://github.com/llvm/llvm-project/pull/85398