configure: Remove non-posix shell expansion

+ change shebang to /bin/sh

Signed-off-by: Petr Vorel <petr.vorel@gmail.com>
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>

configure

@@ -1,4 +1,4 @@
-#! /bin/bash
+#!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 # This is not an autoconf generated configure
 #
@@ -180,7 +180,8 @@ check_ipt_lib_dir()
 
 	for dir in /lib /usr/lib /usr/local/lib
 	do
-		for file in $dir/{xtables,iptables}/lib*t_*so ; do
+		for file in "xtables" "iptables"; do
+			file="$dir/$file/lib*t_*so"
 			if [ -f $file ]; then
 				echo ${file%/*}
 				echo "IPT_LIB_DIR:=${file%/*}" >> $CONFIG