resolve: add error message when resolving using SIGALRM

Closes #1066

lib/hostip.c

@@ -603,11 +603,14 @@ int Curl_resolv_timeout(struct connectdata *conn,
     /* USE_ALARM_TIMEOUT defined, but no timeout actually requested */
     return Curl_resolv(conn, hostname, port, entry);
 
-  if(timeout < 1000)
+  if(timeout < 1000) {
     /* The alarm() function only provides integer second resolution, so if
        we want to wait less than one second we must bail out already now. */
+    failf(data,
+        "remaining timeout of %ld too small to resolve via SIGALRM method",
+        timeout);
     return CURLRESOLV_TIMEDOUT;
-
+  }
   /* This allows us to time-out from the name resolver, as the timeout
      will generate a signal and we will siglongjmp() from that here.
      This technique has problems (see alarmfunc).