[clang] [Clang][CodeGen] Track EH cleanup depth for guarded init and pop correctly (PR #199508)

[Akira Hatanaka via cfe-commits]

ahatanak wrote:

My objective is that the compiler doesn't crash and doesn't generate incorrect code.

The capture lifetime rule has been in place since 2012 (documented in `BlockLanguageSpec.rst`, describing behavior that already existed according to d014c9e6f787010474130b710398fdf90b1550bc), so changing it now seems risky.

https://github.com/llvm/llvm-project/pull/199508