pack: Honor command-line options related to the store.

* guix/scripts/pack.scm (guix-pack): Call
'set-build-options-from-command-line'.

guix/scripts/pack.scm

@@ -284,6 +284,9 @@ (define opts
              (symlinks   (assoc-ref opts 'symlinks))
              (localstatedir? (assoc-ref opts 'localstatedir?)))
         (with-store store
+          ;; Set the build options before we do anything else.
+          (set-build-options-from-command-line store opts)
+
           (run-with-store store
             (mlet* %store-monad ((profile (profile-derivation
                                            (packages->manifest packages)))