c++: `has_value()` function marked as generic Name rather than Function.Name

Another change I noticed when bumping from 2.6.1 to 2.7.1, probably as part of <https://github.com/pygments/pygments/commit/fc56ab883a80f6182339d7fbf95e531ff32e4809>.

In the following code:

```cpp
constexpr bool has_value() const noexcept;
```

`has_value` was previously marked as Name.Function, but now it's marked as just Name. I suspect it should still be Name.Function.