Remove no-longer-needed integer overflow code
* lisp/calculator.el (calculator-number-to-string): Use truncate, not calculator-truncate, since integer overflow cannot occur here. * lisp/calendar/cal-persia.el (calendar-persian-year-from-absolute): * lisp/gnus/gnus-agent.el (gnus-agent-read-article-number): * lisp/gnus/nnmaildir.el (nnmaildir--group-maxnum) (nnmaildir--new-number): * lisp/scroll-bar.el (scroll-bar-scale): * lisp/simple.el (beginning-of-buffer, end-of-buffer): Simplify, now that integer overflow cannot occur.