make Pin hashable

[dhalbert]

Fixes #6179.

I keep encountering cases where I would like to microcontroller.Pin objects to be in a set() or be dictionary keys.

[jepler]

Can you use this existing function?

mp_obj_t mp_generic_unary_op(mp_unary_op_t op, mp_obj_t o_in) {
    switch (op) {
        case MP_UNARY_OP_HASH:
            return MP_OBJ_NEW_SMALL_INT((mp_uint_t)o_in);
        default:
            return MP_OBJ_NULL;      // op not supported
    }    
}

It's used, for instance, for function objects unary op slot so that they can be set members...

[dhalbert]

Can you use this existing function?

Oh, sure, I didn't realize it existed. I have some other places I can use it too.

[jepler]

Thank you! Looks good, didn't test. Too bad none of the other savings are in things enabled in our tiniest ports.

[jepler]

I don't see what changed since the previous iteration, still looks OK as long as it's green.

[dhalbert]

There was a stray < character at the end of one file, I think from typing in the wrong window. Thanks!