Don't poll showmyip.com, it doesn't exist anymore

Fixes #4679.

This leaves us with only one candidate, checkip.dyndns.org.
GetMyExternalIP should be phased out as soon as possible.

src/net.cpp

@@ -368,7 +368,7 @@ bool GetMyExternalIP(CNetAddr& ipRet)
     const char* pszKeyword;
 
     for (int nLookup = 0; nLookup <= 1; nLookup++)
-    for (int nHost = 1; nHost <= 2; nHost++)
+    for (int nHost = 1; nHost <= 1; nHost++)
     {
         // We should be phasing out our use of sites like these. If we need
         // replacements, we should ask for volunteers to put this simple
@@ -393,25 +393,6 @@ bool GetMyExternalIP(CNetAddr& ipRet)
 
             pszKeyword = "Address:";
         }
-        else if (nHost == 2)
-        {
-            addrConnect = CService("74.208.43.192", 80); // www.showmyip.com
-
-            if (nLookup == 1)
-            {
-                CService addrIP("www.showmyip.com", 80, true);
-                if (addrIP.IsValid())
-                    addrConnect = addrIP;
-            }
-
-            pszGet = "GET /simple/ HTTP/1.1\r\n"
-                     "Host: www.showmyip.com\r\n"
-                     "User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)\r\n"
-                     "Connection: close\r\n"
-                     "\r\n";
-
-            pszKeyword = NULL; // Returns just IP address
-        }
 
         if (GetMyExternalIP2(addrConnect, pszGet, pszKeyword, ipRet))
             return true;