- Check some specific IFs first in ipv6_autoconfif().

- $ipv6_enable supports YES|TRUE|ON|1 as in checkyesno().

Based on:	changes in r206408 by dougb

etc/network.subr

@@ -108,7 +108,7 @@ ifconfig_up()
 
 			# backward compatibility: $ipv6_enable
 			case $ipv6_enable in
-			[Yy][Ee][Ss])
+			[Yy][Ee][Ss]|[Tt][Rr][Uu][Ee]|[Oo][Nn]|1)
 				_ipv6_opts="${_ipv6_opts} accept_rtadv"
 				;;
 			esac
@@ -385,6 +385,7 @@ noafif()
 	an[0-9]*|\
 	ath[0-9]*|\
 	ipw[0-9]*|\
+	ipfw[0-9]*|\
 	iwi[0-9]*|\
 	iwn[0-9]*|\
 	ral[0-9]*|\
@@ -444,10 +445,19 @@ ipv6_autoconfif()
 	local _if _tmpargs _arg
 	_if=$1
 
-	if ! ipv6if $_if; then
+	case $_if in
+	lo0|\
+	stf[0-9]*|\
+	faith[0-9]*|\
+	lp[0-9]*|\
+	sl[0-9]*)
+		return 1
+		;;
+	esac
+	if noafif $_if; then
 		return 1
 	fi
-	if noafif $_if; then
+	if ! ipv6if $_if; then
 		return 1
 	fi
 	if checkyesno ipv6_gateway_enable; then
@@ -457,24 +467,11 @@ ipv6_autoconfif()
 	if [ -n "${_tmpargs}" ]; then
 		return 1
 	fi
-
-	case $_if in
-	lo0|\
-	stf[0-9]*|\
-	faith[0-9]*|\
-	lp[0-9]*|\
-	sl[0-9]*|\
-	pflog[0-9]*|\
-	pfsync[0-9]*)
-		return 1
-		;;
-	esac
-
 	# backward compatibility: $ipv6_enable
 	case $ipv6_enable in
-	[Yy][Ee][Ss])
+	[Yy][Ee][Ss]|[Tt][Rr][Uu][Ee]|[Oo][Nn]|1)
 		return 0
-		;;
+	;;
 	esac
 
 	_tmpargs=`_ifconfig_getargs $_if ipv6`