Pull up following revision(s) (requested by tsutsui in ticket #1281):

distrib/miniroot/install.sub: revision 1.60

Handle recent ifconfig(8) outputs in the miniroot installation script.

- Remove netmask slash notation for IP addresses,
  which has been changed between NetBSD 7.x and 8.0:
  http://cvsweb.netbsd.org/bsdweb.cgi/src/sbin/ifconfig/af_inet.c#rev1.24

- Ignore inet6 entries, which miniroot scripts don't support

Should be pulled up to netbsd-9 and netbsd-8.

distrib/miniroot/install.sub

@@ -1,5 +1,5 @@
 #!/bin/sh
-#	$NetBSD: install.sub,v 1.48.2.4 2020/12/14 17:26:36 martin Exp $
+#	$NetBSD: install.sub,v 1.48.2.5 2021/06/05 10:40:08 martin Exp $
 #
 # Copyright (c) 1996 The NetBSD Foundation, Inc.
 # All rights reserved.
@@ -403,8 +403,9 @@ configure_ifs() {
 	fi
 
 	set -- $(ifconfig $_interface_name | sed -n '
-		/^[ 	]*inet/{
+		/^[ 	]*inet /{
 		s/inet//
+		s,/[0-9]*,,
 		s/--> [0-9.][0-9.]*//
 		s/netmask//
 		s/broadcast//