Turn off automatic link local address if ipv6_enable is not set to YES

in rc.conf

Reviewed by:    KAME core team, cperciva
MFC after:      3 days

etc/network.subr

@@ -41,6 +41,10 @@ ifconfig_up()
 {
 	_cfg=1
 
+	if checkyesno ipv6_enable; then
+		${SYSCTL_W} net.inet6.ip6.auto_linklocal=1
+	fi
+
 	ifconfig_args=`ifconfig_getargs $1`
 	if [ -n "${ifconfig_args}" ]; then
 		ifconfig $1 up

sys/netinet6/in6_ifattach.c

@@ -63,7 +63,7 @@ unsigned long in6_maxmtu = 0;
 #ifdef IP6_AUTO_LINKLOCAL
 int ip6_auto_linklocal = IP6_AUTO_LINKLOCAL;
 #else
-int ip6_auto_linklocal = 1;	/* enable by default */
+int ip6_auto_linklocal = 0;	/* disable by default */
 #endif
 
 struct callout in6_tmpaddrtimer_ch;