[clang] [Clang] Emit error for duplicate mangled names within a lambda (PR #107581)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

Can you add a testcase that doesn't involve lambdas?  Maybe something like the following:

```
inline void f(int) asm("foo");
inline void f(int) {}
inline void f() asm("foo");
inline void f(){}
```

https://github.com/llvm/llvm-project/pull/107581