Fix off-by-one error in max line length so lines do not wrap

Occasionally auto-formatted lines would wrap to the next line since they
exceeded the max length by one character. Subtracting 1 from the max line length
fixes the issues in these scenarios (both "wrap_width" and "rulers" were 81 in
my case; setting the max auto-formatted line length to 80 correctly formats a
previously overflowing comment).