add support for "proxy_dns_old" to use old 3.1 DNS lookup method

some lamer on IRC by the name of annoner/R3M0RS3/penis was complaining
that 3.1 is a lot better than proxychains-ng, because it happens to
work with the browser he's interested in.
since this wasn't the first time this is requested, let's give this
those lamers what they want: lame code!

src/proxyresolv

@@ -1,10 +1,8 @@
 #!/bin/sh
-# This is a legacy script that uses "dig" to do DNS lookups via TCP.
-# it is not actively maintained since proxychains no longer depends
-# on it. i leave it here as a bonus.
+# This is a legacy script that uses "dig" or "drill" to do DNS lookups via TCP.
 
 # DNS server used to resolve names
-DNS_SERVER=8.8.8.8
+test -z "$DNS_SERVER" && DNS_SERVER=8.8.8.8
 
 
 if [ $# = 0 ] ; then
@@ -14,5 +12,12 @@ if [ $# = 0 ] ; then
 fi
 
 
-export LD_PRELOAD=libproxychains4.so
-dig $1 @$DNS_SERVER +tcp | awk '/A.?[0-9]+\.[0-9]+\.[0-9]/{print $5;}'
+test -z $LD_PRELOAD && export LD_PRELOAD=libproxychains4.so
+
+if type dig 1>/dev/null 2>&1 ; then
+dig       $1 @$DNS_SERVER +tcp | awk '/A.?[0-9]+\.[0-9]+\.[0-9]/{print $5;}'
+elif type drill 1>/dev/null 2>&1 ; then
+drill -t4 $1 @$DNS_SERVER      | awk '/A.+[0-9]+\.[0-9]+\.[0-9]/{print $5;}'
+else
+echo "error: neither dig nor drill found" >&2
+fi