Hello!

As a follow up to my previous patch to mcron2, this completes the wrap
phases and fix a small issue where the mcron modules were installed to
share/guile/site/2.0 instead of 2.2.

For those using dyndns services, a job like the following should now
work without having to propagate Guile or GnuTLS in your user/system
profile[0]:

--8<---------------cut here---------------start------------->8---
;;; Secrets defined as variables prefixed by "sec-".
(include "/abs/path/to/your/secrets.scm")

(define duckdns-job
  ;; Update personal domain IP every 5 minutes.
  #~(job '(next-minute (range 0 60 5))
	 (lambda ()
	   (use-modules (web client))
	   (http-get
	    (string-append
	     "https://www.duckdns.org/update?domains=apteryx&token="
	     #$sec-dyndns-token "&ip=")))))

(operating-system
 ...
 (services
  (cons*
   (mcron-service (list duckdns-job))
   ...
--8<---------------cut here---------------end--------------->8---

I had tested my previous patch as a user (where Guile and GnuTLS were
installed), so it was working, but after testing from the "real" herd
service (which runs as root), it was failing, not finding the (web
client) and GnuTLS modules.

The attached patch fixes that.