Remove useless else branch in the $smart_wrap code. (see #3857)

Remove useless else branch in the $smart_wrap code. (see #3857)

Thanks to Vincent Lefèvre for noticing the nested else was redundant,
since buf_ptr is already set to "buf + cnt" after the format_line()
call.

This allows us to merge the inner and outer if statement, resulting in
simpler code.