Don't use the function call width heuristic for tuples

[nrc]

It's kinda silly:

-            (buf.offset(tydesc_start as isize), buf.offset(start as isize))
+            (buf.offset(tydesc_start as isize),
+             buf.offset(start as isize))

[marcusklaas]

Should we not? I think an argument can be made in favour of the heuristic for tuples. They are pretty much function calls without a path any way..

[nrc]

I guess I just prefer the one line version in the example above - multi-line tuples look a bit weird to me. Not sure I can explain it logically. It does seem to be borne out empirically in the reformatting we do though.