Use command substitution instead of raw keys in more places

Use command substitution instead of raw keys in more places

* admin/authors.el (authors):
* lisp/abbrev.el (abbrev-suggest-show-report):
* lisp/calc/calc.el (calc-display-trail, calc):
* lisp/completion.el (completion-locate-db-error):
* lisp/dired-x.el (dired-extra-startup):
* lisp/emacs-lisp/package.el (package-install-selected-packages):
* lisp/emulation/viper.el (viper-mode):
* lisp/facemenu.el (list-colors-display):
* lisp/mail/emacsbug.el (report-emacs-bug-hook):
* lisp/mail/sendmail.el (mail):
* lisp/menu-bar.el (menu-bar-mode):
* lisp/org/org.el (org-revert-all-org-buffers):
* lisp/progmodes/antlr-mode.el (antlr-help-rules-intro)
(antlr-insert-makefile-rules):
* lisp/progmodes/gdb-mi.el (gdb--check-interpreter):
* lisp/progmodes/xscheme.el (xscheme-process-sentinel):
* lisp/ps-print.el (ps-font-info-database):
* lisp/recentf.el (recentf-edit-list, recentf-open-files):
* lisp/vc/ediff-util.el (ediff-suspend):
* lisp/vc/pcvs.el (cvs-mode):
* lisp/vc/vc-bzr.el (vc-bzr-dir-extra-headers): Use command
substitution.