Overflow in Range<A> size_hint() 

`size_hint` is not implemented correctly for the ranges, it overflows:

```
playbot: (-1i8..127).size_hint()
-playbot:#rust-internals- (18446744073709551488, Some(18446744073709551488))
```

Expected result: 128

With other compilation settings, the result is:

```
'Error: arithmetic operation overflowed'
```
