Allegro hack for REQUIRE Re: MK:DEFSYSTEM

 [CC attempted to allegro mailing list, to report the issue at [1],
   and to solicit comments/suggestions on how better to do this]

Helu, This is pretty gross, but may be less gross than redefining
REQUIRE on allegro.  It makes use of the :CALL search list
functionality, to sneakily load the module via defsystem.

(defun allegro-mk-defsystem-module-provider-hack
     (name search-list order check-bundle whatnow);[1]
     (declare (ignore search-list order check-bundle whatnow))
  (let ((module-name (string-downcase (string name)))
	(dummy-return (mk::compute-system-path (string-downcase name) NIL)))
    (when (mk:find-system module-name :load-or-nil)
      (mk:load-system module-name
		      :compile-during-load t
		      :verbose nil)
      dummy-return))) ;[2]

;; ingratiate into sys::*require-search-list* 
(let ((form '(:CALL allegro-mk-defsystem-module-provider-hack)))
  (unless (find form sys::*require-search-list* :test #'equal)
    (setq sys::*require-search-list*
	  (append sys::*require-search-list* (list form)))))

;;[1] allegro_acl81 docs at the end of
;;  <URL:http://www.franz.com/support/documentation/8.1/doc/loading.htm#search-list-example-2>
;;  mention this function will be called with 4 args but the function
;;  gets called with 5 .

;;[2] the return value is the sysdef file which gets wastefully loaded