add statements to check the preset files

ss-tproxy

@@ -8,6 +8,11 @@ else
     exit 1
 fi
 
+[ ! -f "$dnsmasq_gfwlist"     ] && { echo "dnsmasq_gfwlist: $dnsmasq_gfwlist: No such file or directory"         1>&2; exit 1; }
+[ ! -f "$dnsmasq_gfwlist_ext" ] && { echo "dnsmasq_gfwlist_ext: $dnsmasq_gfwlist_ext: No such file or directory" 1>&2; exit 1; }
+[ ! -f "$chinadns_chnroute"   ] && { echo "chinadns_chnroute: $chinadns_chnroute: No such file or directory"     1>&2; exit 1; }
+[ ! -f "$iptables_ipset_file" ] && { echo "iptables_ipset_file: $iptables_ipset_file: No such file or directory" 1>&2; exit 1; }
+
 function check_depend {
 case "$mode" in
     tproxy_global)