Move OS/compiler/feature detection to public v8config.h header.

include/v8stdint.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 15 matching lines @@
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // Load definitions of standard types.
 
 #ifndef V8STDINT_H_
 #define V8STDINT_H_
 
 #include <stddef.h>
 #include <stdio.h>
 
-#if defined(_WIN32) && !defined(__MINGW32__)
+#include "v8config.h"
+
+#if V8_OS_WIN && !V8_CC_MINGW
 
 typedef signed char int8_t;
 typedef unsigned char uint8_t;
 typedef short int16_t;  // NOLINT
 typedef unsigned short uint16_t;  // NOLINT
 typedef int int32_t;
 typedef unsigned int uint32_t;
 typedef __int64 int64_t;
 typedef unsigned __int64 uint64_t;
 // intptr_t and friends are defined in crtdefs.h through stdio.h.
 
 #else
 
-#include <stdint.h>
+#include <stdint.h>  // NOLINT
 
 #endif
 
 #endif  // V8STDINT_H_