Arch Linux does not provide pax anymore

https://lists.archlinux.org/pipermail/arch-general/2017-April/043604.html

bootstrap/bootstrap

@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# $NetBSD: bootstrap,v 1.253 2018/10/28 18:41:41 sevan Exp $
+# $NetBSD: bootstrap,v 1.254 2018/10/29 15:16:32 triaxx Exp $
 #
 # Copyright (c) 2001-2011 Alistair Crooks <agc@NetBSD.org>
 # All rights reserved.
@@ -718,6 +718,10 @@ Linux)
 		need_awk=no
 		need_sed=no
 	fi
+  # Arch does not provide pax anymore
+  if [ -f /etc/arch-release ]; then
+    need_pax=yes
+  fi
 	set_opsys=no
 	machine_arch=`uname -m`
 	# Override machine_arch where required.
@@ -1353,6 +1357,9 @@ esac
 case "$need_extras" in
 yes)	build_package "pkgtools/bootstrap-extras";;
 esac
+case "$need_pax" in
+yes)    build_package "archivers/pax"
+esac
 build_package "pkgtools/pkg_install"
 
 etc_mk_conf="$sysconfdir/mk.conf"