ImportC: Macros inside a typedef enum not seen

## Atila Neves (@atilaneves) reported this on 2024-02-28T08:38:24Z

### Transferred from https://issues.dlang.org/show_bug.cgi?id=24419

### Description

````markdown
------
// quux.c
typedef enum {
    #define R0 _RAX
    _RAX,
} reg;

// mod.d
import quux;
const _ = _RAX; // fine
const r0 = R0;  // oops
------

source/mod.d(3): Error: undefined identifier `R0`, did you mean variable `r0`?
````