libs/sgi-uhttpd: fix binding to properly work with current uhttpd2 implementation

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

git-svn-id: http://svn.luci.subsignal.org/luci/trunk@9963 ab181a69-ba2e-0410-a84d-ff88ab4c47bc