Move all the HAVE() macros related to string manipulations to wtf/StringExtras.h.

Source/wtf/Platform.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007-2009 Torch Mobile, Inc.
  * Copyright (C) 2010, 2011 Research In Motion Limited. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 120 matching lines @@
 #define WTF_USE_SYSTEM_MALLOC 1
 #endif /* OS(DARWIN) */
 
 #if !defined(HAVE_ACCESSIBILITY)
 #define HAVE_ACCESSIBILITY 1
 #endif /* !defined(HAVE_ACCESSIBILITY) */
 
 #if OS(UNIX)
 #define HAVE_MMAP 1
 #define HAVE_SIGNAL_H 1
-#define HAVE_STRINGS_H 1
 #define HAVE_SYS_TIME_H 1
 #define WTF_USE_PTHREADS 1
 #endif /* OS(UNIX) */
 
 #if (OS(FREEBSD) || OS(OPENBSD)) && !defined(__GLIBC__)
 #define HAVE_PTHREAD_NP_H 1
 #endif
 
 #if !defined(HAVE_VASPRINTF)
 #if !COMPILER(MSVC)
 #define HAVE_VASPRINTF 1
 #endif
 #endif
 
-#if !defined(HAVE_STRNSTR)
-#if OS(DARWIN) || (OS(FREEBSD) && !defined(__GLIBC__))
-#define HAVE_STRNSTR 1
-#endif
-#endif
-
 #if !OS(WINDOWS) && !OS(SOLARIS) && !OS(ANDROID)
 #define HAVE_TM_GMTOFF 1
 #define HAVE_TM_ZONE 1
 #define HAVE_TIMEGM 1
 #endif
 
 #if OS(DARWIN)
 #define HAVE_DISPATCH_H 1
 #define HAVE_MADV_FREE 1
 #define HAVE_PTHREAD_SETNAME_NP 1
 #define HAVE_MADV_FREE_REUSE 1
 #endif /* OS(DARWIN) */
 
 #if OS(WINDOWS)
 #define HAVE_ISDEBUGGERPRESENT 1
 #define HAVE_VIRTUALALLOC 1
 #endif
 
 #endif /* WTF_Platform_h */