build-system/glib-or-gtk: Wrap libexec programs.

* guix/build/glib-or-gtk-build-system.scm (wrap-all-programs): Also
  wrap binaries in libexec/, such as those launched by dbus services.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

guix/build/glib-or-gtk-build-system.scm

@@ -140,7 +140,9 @@ (define handle-output
      ((output . directory)
       (unless (member output glib-or-gtk-wrap-excluded-outputs)
         (let* ((bindir       (string-append directory "/bin"))
-               (bin-list     (find-files bindir ".*"))
+               (libexecdir   (string-append directory "/libexec"))
+               (bin-list     (append (find-files bindir ".*")
+                                     (find-files libexecdir ".*")))
                (datadirs     (data-directories
                               (alist-cons output directory inputs)))
                (gtk-mod-dirs (gtk-module-directories