Remove redundant :group args in progmodes/*.el

Remove redundant :group args in progmodes/*.el

* lisp/progmodes/bug-reference.el:
* lisp/progmodes/cfengine.el:
* lisp/progmodes/cmacexp.el:
* lisp/progmodes/cpp.el:
* lisp/progmodes/cwarn.el:
* lisp/progmodes/dcl-mode.el:
* lisp/progmodes/executable.el:
* lisp/progmodes/flymake.el:
* lisp/progmodes/gud.el:
* lisp/progmodes/hideshow.el:
* lisp/progmodes/icon.el:
* lisp/progmodes/inf-lisp.el:
* lisp/progmodes/js.el:
* lisp/progmodes/ld-script.el:
* lisp/progmodes/make-mode.el:
* lisp/progmodes/modula2.el:
* lisp/progmodes/pascal.el:
* lisp/progmodes/perl-mode.el:
* lisp/progmodes/prog-mode.el:
* lisp/progmodes/simula.el:
* lisp/progmodes/xscheme.el: Remove redundant :group args.