What is the purpose of PINCOUNT_fn

In commit a536cc8 the function `PINCOUNT_fn` was introduced with a very limited commit description "make PINS_COUNT dynamic". Forgive my ignorance, but I don't see anything dynamic in the implementation.

```
extern "C" {
unsigned int PINCOUNT_fn() {
return (sizeof(g_APinDescription) / sizeof(g_APinDescription[0]));
}
}
```

Why is it necessary to repeat the implementation for every variant? Why not put it in `wiring_private.c` or something?

And look at the modifications in all the `variants.h`. The function is declared twice? In commit 92efd745 a second declaraion was added. Why?

Start by reading commit a536cc8 and commit 92efd745, then inspect PINCOUNT_fn in each variant and its declarations in the variants.h files. Compare those implementations with wiring_private.c to determine why the function is repeated and declared twice. Done means documenting the intended purpose and deciding whether the duplication or declarations should change.

Written by the indexing model from the issue text.