[juhosg: add missing symbols to config-3.{7,8}]

Patch from: Дмитрий Лебедев <lebedev@trendnet.ru>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@35970 3c298f89-4303-0410-b956-a3cf2f4a3e73