Eliminate HAVE(ERRNO_H) guard.

Source/wtf/DateMath.cpp

 /*
  * Copyright (C) 1999-2000 Harri Porten (porten@kde.org)
  * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2007-2009 Torch Mobile, Inc.
  * Copyright (C) 2010 &yet, LLC. (nate@andyet.net)
  *
  * The Original Code is Mozilla Communicator client code, released
  * March 31, 1998.
  *
@@ skipping 72 matching lines @@
 #include <limits.h>
 #include <limits>
 #include <stdint.h>
 #include <time.h>
 #include "wtf/text/StringBuilder.h"
 
 #if OS(WINDOWS)
 #include <windows.h>
 #endif
 
-#if HAVE(ERRNO_H)
-#include <errno.h>
-#endif
-
 #if HAVE(SYS_TIME_H)
 #include <sys/time.h>
 #endif
 
 #if HAVE(SYS_TIMEB_H)
 #include <sys/timeb.h>
 #endif
 
 using namespace WTF;
 
@@ skipping 979 matching lines @@
 
     stringBuilder.append(utcOffset > 0 ? '+' : '-');
     int absoluteUTCOffset = abs(utcOffset);
     stringBuilder.append(twoDigitStringFromNumber(absoluteUTCOffset / 60));
     stringBuilder.append(twoDigitStringFromNumber(absoluteUTCOffset % 60));
 
     return stringBuilder.toString();
 }
 
 } // namespace WTF