Default OS to nextstep if machine vendor is Next.

-ns2 is an alias for -nextstep.

From-SVN: r11041

gcc/config.sub

@@ -676,6 +676,9 @@ case $os in
 	-ctix* | -uts*)
 		os=-sysv
 		;;
+	-ns2 )
+	        os=-nextstep2
+		;;
 	# Preserve the version number of sinix5.
 	-sinix5.*)
 		os=`echo $os | sed -e 's|sinix|sysv|'`
@@ -783,6 +786,9 @@ case $basic_machine in
 	m88k-omron*)
 		os=-luna
 		;;
+	*-next )
+		os=-nextstep
+		;;
 	*-sequent)
 		os=-ptx
 		;;