Start better error reporting for sockets

runtime/bin/utils_win.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include <errno.h>
 
 #include "bin/utils.h"
 
-OSError::OSError() : code_(0), message_(NULL) {
+OSError::OSError() : sub_system_(kSystem), code_(0), message_(NULL) {
   set_code(GetLastError());
 
   static const int kMaxMessageLength = 256;
   char message[kMaxMessageLength];
   DWORD message_size =
       FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                     NULL,
                     code_,
                     MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                     message,
                     kMaxMessageLength,
                     NULL);
   if (message_size == 0) {
     if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
       fprintf(stderr, "FormatMessage failed %d\n", GetLastError());
     }
     snprintf(message, kMaxMessageLength, "OS Error %d", code_);
   }
   message[kMaxMessageLength - 1] = '\0';
 
   SetMessage(message);
 }