router_readconfig: avoid use after free found by Coverity
router_readconfig: avoid use after free found by Coverity

grobian/carbon-c-relay,piotr1212/carbon-c-relay,piotr1212/carbon-c-relay,grobian/carbon-c-relay,piotr1212/carbon-c-relay,grobian/carbon-c-relay,piotr1212/carbon-c-relay