Header parser sees `using std::int32_t` as redefinition

With the following declarations

```c++
#include <cstdint>
#include <vector>

using std::int8_t;
using std::int16_t;
using std::int32_t;
```

the header parser fails and reports this error:

```
Error: Failed to parse input file 'source/structures.h', aborting
       TYPE_REDEFINITION at position 98 (line 8)
       ...e <vector>    using std::int8_t;  using std::int16_t;  using std...
```