[clang] [clang][Sema] Don't issue -Wcast-function-type-mismatch for enums with a matching underlying type (PR #87793)

[Aaron Ballman via cfe-commits]

================
@@ -19,8 +19,12 @@ f5 *e;
 f6 *f;
 f7 *g;
 
+enum E : long;
----------------
AaronBallman wrote:

Another test that would be helpful would be a test not using a fixed underlying type but still produces a type compatible with `long`, as in:
```
enum E {
  Big = __LONG_MAX__
};
```

https://github.com/llvm/llvm-project/pull/87793