hydra: services: Allow reading from /var/lib/qa-frontpage.

Because this will allow NGinx to read and serve specific files from
this directory.

* hydra/modules/sysadmin/services.scm (qa-frontpage-activation): New
procedure.
(qa-frontpage-service-type): Extend the activation-service-type.

hydra/modules/sysadmin/services.scm

@@ -1147,6 +1147,12 @@ to a selected directory.")
            (stop #~(make-kill-destructor))
            (documentation "Run the QA Frontpage.")))))
 
+(define (qa-frontpage-activation config)
+  (with-imported-modules '((guix build utils))
+    #~(begin
+        (use-modules (guix build utils))
+        (chmod "/var/lib/qa-frontpage" #o755))))
+
 (define %qa-frontpage-accounts
   (list (user-account
          (name "qa-frontpage")
@@ -1164,6 +1170,8 @@ to a selected directory.")
    (name 'qa-frontpage)
    (extensions (list (service-extension account-service-type
                                         (const %qa-frontpage-accounts))
+                     (service-extension activation-service-type
+                                        qa-frontpage-activation)
                      (service-extension shepherd-root-service-type
                                         qa-frontpage-shepherd-services)))
    (default-value (qa-frontpage-configuration))