multi: connect fail => use next IP address

When using the multi interface and connecting to a host name that
resolves to multiple IP addresses, there was no logic that made it
continue to the next IP if connecting to the first address times
out. This is now corrected.

lib/urldata.h

@@ -812,6 +812,15 @@ struct connectdata {
 
   struct ConnectBits bits;    /* various state-flags for this connection */
 
+ /* connecttime: when connect() is called on the current IP address. Used to
+    be able to track when to move on to try next IP - but only when the multi
+    interface is used. */
+  struct timeval connecttime;
+  /* The two fields below get set in Curl_connecthost */
+  int num_addr; /* number of addresses to try to connect to */
+  long timeoutms_per_addr; /* how long time in milliseconds to spend on
+                              trying to connect to each IP address */
+
   const struct Curl_handler * handler;  /* Connection's protocol handler. */
 
   long ip_version; /* copied from the SessionHandle at creation time */