Use t for non-nil default values in boolean defcustom declarations

* lisp/emulation/viper-ex.el (ex-unix-type-shell):
* lisp/emulation/viper-init.el (viper-ms-style-os-p):
* lisp/eshell/em-glob.el (eshell-glob-case-insensitive):
* lisp/filecache.el (file-cache-ignore-case):
* lisp/lpr.el (lpr-add-switches):
* lisp/ls-lisp.el (ls-lisp-ignore-case):
* lisp/mail/binhex.el (binhex-use-external):
* lisp/progmodes/cperl-mode.el (cperl-electric-parens-mark):
Normalise default values to nil or t.

1 files changed, 2 insertions, 1 deletions

diff --git a/lisp/lpr.el b/lisp/lpr.el
index af59a953f38..6b8343b695d 100644
--- a/lisp/lpr.el
+++ b/lisp/lpr.el
@@ -73,7 +73,8 @@ switch on this list.
 See `lpr-command'."
   :type '(repeat (string :tag "Argument")))
 
-(defcustom lpr-add-switches (memq system-type '(berkeley-unix gnu/linux))
+(defcustom lpr-add-switches
+  (not (not (memq system-type '(berkeley-unix gnu/linux))))
   "Non-nil means construct `-T' and `-J' options for the printer program.
 These are made assuming that the program is `lpr';
 if you are using some other incompatible printer program,