gnu: dbus-1.10.12: Fix search paths.

Add the patches from dbus's source field back into its replacement. This ensures
that the grafted dbus package can find its services on GuixSD.

This is a follow-up to commit 34f9582aad.

* gnu/packages/glib.scm (dbus-1.10.12)[source]: Inherit from dbus.

Signed-off-by: Leo Famulari <leo@famulari.name>

gnu/packages/glib.scm

@@ -139,7 +139,7 @@ shared NFS home directories.")
     (source
       (let ((version "1.10.12"))
         (origin
-          (method url-fetch)
+          (inherit (package-source dbus))
           (uri (string-append
                 "https://dbus.freedesktop.org/releases/dbus/dbus-"
                 version ".tar.gz"))