awk: Fix handling of functions with empty body

Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
udhcpd: add -I LOCAL_ADDR option

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
udhcpd: also add -I ADDR to help text

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>