Don't print tuplet bracket when tuplet number is wider

This was already part of the code. However, because scm_is_true yields true unless it's false, the condition that turned the bracket visibility off when the tuplet number is wider than the tuplet bracket was never true in this case, and as consequence a tuplet bracket was still being printed even when it shouldn't, resulting in negative lengths (i.e. "inside-out brackets").

Closes #3901 (closed)