[clang] [Clang] Introduce OverflowBehaviorType for fine-grained overflow control (PR #148914)

[Matheus Izvekov via cfe-commits]

https://github.com/mizvekov commented:

How about inner qualifiers? The patch doesn't address the situation.

For a test like:
```C++
using ConstInt = const int;
using WrapConstInt1 = ConstInt __attribute__((overflow_behavior(wrap)));
using WrapConstInt2 = const int __attribute__((overflow_behavior(wrap)));
```
WrapConstInt1 and WrapConstInt2 should be the same type, as this is what makes most sense, I think.

This would be the same rules as qualifiers on array types, the inner and outer qualifiers mean the same thing and are added together for canonicalization.

https://github.com/llvm/llvm-project/pull/148914