bug: fail to parse statements interleaved with preprocessor directives

The following code fails to get parsed

```cpp
class
#ifdef FOO
Foo
#else
Bar
#endif
{
}
```

Possible naive solution: parse preprocessor directives as "extras" and inject another ad-hoc parser
~~Proper solution: check how other C languages parsers have them implemented~~
*(other parsers also fail on such scenarios)*