Fix a span in `parse_ty_bare_fn`.
It currently goes one token too far.
Example: line 259 of `tests/ui/abi/compatibility.rs`:
```
test_abi_compatible!(fn_fn, fn(), fn(i32) -> i32);
```
This commit changes the span for the second element from `fn(),` to `fn()`, i.e. removes the extraneous comma.
This doesn't affect any tests. I found it while debugging some other code. Not a big deal but an easy fix so I figure it worth doing.
r? ``@spastorino``
dd6b04663e