Also create .gz images if configured to do so.
This is equivalent, but different to what we have in trunk, as the image
creation has been rewritten there.
Signed-off-by: Bruno Randolf <br1@einfach.org>
git-svn-id: svn://svn.openwrt.org/openwrt/branches/chaos_calmer@47604 3c298f89-4303-0410-b956-a3cf2f4a3e73
