[clang] [Clang] Fix Itanium mangling crash for local lambda in ctor/dtor (PR #181068)

[Eli Friedman via cfe-commits]

https://github.com/efriedma-quic commented:

The test coverage here seems deficient: nothing is actually checking that the mangling that was causing the crash.

Also, for the names that are covered, the mangling seems to be inconsistent with gcc.

https://github.com/llvm/llvm-project/pull/181068