Turn libplatform into a component

src/base/compiler-specific.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_BASE_COMPILER_SPECIFIC_H_
 #define V8_BASE_COMPILER_SPECIFIC_H_
 
 #include "include/v8config.h"
 
 // Annotate a typedef or function indicating it's ok if it's not used.
@@ skipping 42 matching lines @@
 //   };
 //
 // In .cc file:
 //   STATIC_CONST_MEMBER_DEFINITION const int Foo::kBar;
 #if V8_HAS_DECLSPEC_SELECTANY
 #define STATIC_CONST_MEMBER_DEFINITION __declspec(selectany)
 #else
 #define STATIC_CONST_MEMBER_DEFINITION
 #endif
 
+#if V8_CC_MSVC
+
+#include <sal.h>
+
+// Macros for suppressing and disabling warnings on MSVC.
+//
+// Warning numbers are enumerated at:
+// http://msdn.microsoft.com/en-us/library/8x5x43k7(VS.80).aspx
+//
+// The warning pragma:
+// http://msdn.microsoft.com/en-us/library/2c8f766e(VS.80).aspx
+//
+// Using __pragma instead of #pragma inside macros:
+// http://msdn.microsoft.com/en-us/library/d9x1s805.aspx
+
+// MSVC_SUPPRESS_WARNING disables warning |n| for the remainder of the line and
+// for the next line of the source file.
+#define MSVC_SUPPRESS_WARNING(n) __pragma(warning(suppress : n))
+
+// Allows exporting a class that inherits from a non-exported base class.
+// This uses suppress instead of push/pop because the delimiter after the
+// declaration (either "," or "{") has to be placed before the pop macro.
+//
+// Example usage:
+// class EXPORT_API Foo : NON_EXPORTED_BASE(public Bar) {
+//
+// MSVC Compiler warning C4275:
+// non dll-interface class 'Bar' used as base for dll-interface class 'Foo'.
+// Note that this is intended to be used only when no access to the base class'
+// static data is done through derived classes or inline methods. For more info,
+// see http://msdn.microsoft.com/en-us/library/3tdb471s(VS.80).aspx
+#define NON_EXPORTED_BASE(code) \
+  MSVC_SUPPRESS_WARNING(4275)   \
+  code
+
+#else  // Not MSVC
+
+#define MSVC_SUPPRESS_WARNING(n)
+#define NON_EXPORTED_BASE(code) code
+
+#endif  // V8_CC_MSVC
+
 #endif  // V8_BASE_COMPILER_SPECIFIC_H_