Fix byte-compiler warnings about looking-back.

Fix byte-compiler warnings about looking-back.

* lisp/vc/log-view.el (log-view-end-of-defun-1):
* lisp/textmodes/tex-mode.el (latex-forward-sexp-1):
* lisp/textmodes/reftex-ref.el (reftex-goto-label):
* lisp/textmodes/bibtex.el (bibtex-insert-kill):
* lisp/progmodes/sh-script.el (sh--maybe-here-document):
* lisp/progmodes/ruby-mode.el (ruby-end-of-defun):
* lisp/progmodes/ada-mode.el (ada-in-numeric-literal-p):
* lisp/org/org.el (org-insert-heading, org-sort-entries):
* lisp/org/org-mouse.el (org-mouse-end-headline)
(org-mouse-context-menu):
* lisp/org/org-clock.el (org-clock-cancel):
* lisp/man.el (Man-default-man-entry):
* lisp/mail/rmail.el (rmail-get-new-mail, rmail-insert-inbox-text)
(rmail-ensure-blank-line):
* lisp/mail/footnote.el (Footnote-delete-footnote):
* lisp/mail/emacsbug.el (report-emacs-bug):
* lisp/info.el (Info-follow-reference, Info-fontify-node):
* lisp/info-look.el (info-lookup-guess-custom-symbol):
* lisp/help-fns.el (help-fns--key-bindings):
* lisp/files.el (hack-local-variables):
* lisp/emulation/viper-ex.el (viper-get-ex-token, ex-cmd-complete)
(viper-get-ex-pat, ex-expand-filsyms, viper-get-ex-file)
(viper-complete-filename-or-exit):
* lisp/emulation/viper-cmd.el (viper-backward-indent):
* lisp/emacs-lisp/lisp-mode.el (calculate-lisp-indent):
* lisp/emacs-lisp/elint.el (elint-get-top-forms):
* lisp/cus-edit.el (custom-face-edit-value-create):
* lisp/calendar/todo-mode.el (todo-set-item-priority)
(todo-filter-items-1, todo-convert-legacy-files)
(todo-prefix-overlays): Add explicit second arg to looking-back.