[clang] [Clang] fix missing source location for ':' error in macro-expanded case statements (PR #143460)

[Eli Friedman via cfe-commits]

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

This seems like a more general issue... some examples:

```
#define D foo bar
enum { D };
```

```
#define D foo bar
void f() { int a[2]; auto [D] = a; }
```

```
#define D <int!
template <class T> class X;
X D;
```

```
#define D C::{
class C { D }};
```

Can we come up with some kind of generalized solution?

https://github.com/llvm/llvm-project/pull/143460