Fix --force-bind logic

Fix --force-bind logic

Quoting Cocagne:

	"line 1280 of autoipd's main.c: "else if (event ==
	EVENT_ROUTABLE_ADDR_CONFIGURED)" is missing '&& !force_bind' in
	the conditional. The lack of this condition causes the local
	link IP to be released even if the --force-bind arugment is
	passed.

	The problem was noticed when attempting to use avahi-autoipd
	acquire a link-local address during the early-userspace in a
	Linux initramfs. Immediately after the call-out script assinged
	the ll-address to the device, the daemon released the address
	via this conditional. It's suspicious that the daemon would
	consider this address "routable" but, even if it were,
	--force-bind should prevent the address from being released.

	After adding the && !force_bind to the conditional the daemon
	appeard to behave as expected."

Closes #209.