Eliminate a unnecessary socket creation in Curl_getaddrinfo for an IPv4

address in an IPv6 capable libcurl.

lib/hostthre.c

@@ -771,14 +771,29 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
   struct addrinfo hints, *res;
   int error;
   char sbuf[NI_MAXSERV];
-  curl_socket_t s;
   int pf;
   struct SessionHandle *data = conn->data;
 
   *waitp = FALSE; /* default to synch response */
 
+  /*
+   * Check if a limited name resolve has been requested.
+   */
+  switch(data->set.ip_version) {
+  case CURL_IPRESOLVE_V4:
+    pf = PF_INET;
+    break;
+  case CURL_IPRESOLVE_V6:
+    pf = PF_INET6;
+    break;
+  default:
+    pf = PF_UNSPEC;
+    break;
+  }
+
+  if (pf != PF_INET) {
     /* see if we have an IPv6 stack */
-  s = socket(PF_INET6, SOCK_DGRAM, 0);
+    curl_socket_t s = socket(PF_INET6, SOCK_DGRAM, 0);
     if(s == CURL_SOCKET_BAD) {
       /* Some non-IPv6 stacks have been found to make very slow name resolves
        * when PF_UNSPEC is used, so thus we switch to a mere PF_INET lookup if
@@ -791,20 +806,6 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
        * possible checks. And close the socket again.
        */
       sclose(s);
-
-    /*
-     * Check if a more limited name resolve has been requested.
-     */
-    switch(data->set.ip_version) {
-    case CURL_IPRESOLVE_V4:
-      pf = PF_INET;
-      break;
-    case CURL_IPRESOLVE_V6:
-      pf = PF_INET6;
-      break;
-    default:
-      pf = PF_UNSPEC;
-      break;
     }
   }