Move V8EXPORT definition to its own file

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 8a6a8c67a7295decec2587f7220368046e829995..35ed5a696bf1b865b2e6d11cd3103a967ffa99c5 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -38,44 +38,9 @@
 #ifndef V8_H_
 #define V8_H_
 
+#include "v8-export.h"
 #include "v8stdint.h"
 
-#ifdef _WIN32
-
-// Setup for Windows DLL export/import. When building the V8 DLL the
-// BUILDING_V8_SHARED needs to be defined. When building a program which uses
-// the V8 DLL USING_V8_SHARED needs to be defined. When either building the V8
-// static library or building a program which uses the V8 static library neither
-// BUILDING_V8_SHARED nor USING_V8_SHARED should be defined.
-#if defined(BUILDING_V8_SHARED) && defined(USING_V8_SHARED)
-#error both BUILDING_V8_SHARED and USING_V8_SHARED are set - please check the\
-  build configuration to ensure that at most one of these is set
-#endif
-
-#ifdef BUILDING_V8_SHARED
-#define V8EXPORT __declspec(dllexport)
-#elif USING_V8_SHARED
-#define V8EXPORT __declspec(dllimport)
-#else
-#define V8EXPORT
-#endif  // BUILDING_V8_SHARED
-
-#else  // _WIN32
-
-// Setup for Linux shared library export.
-#if defined(__GNUC__) && ((__GNUC__ >= 4) || \
-    (__GNUC__ == 3 && __GNUC_MINOR__ >= 3)) && defined(V8_SHARED)
-#ifdef BUILDING_V8_SHARED
-#define V8EXPORT __attribute__ ((visibility("default")))
-#else
-#define V8EXPORT
-#endif
-#else
-#define V8EXPORT
-#endif
-
-#endif  // _WIN32
-
 #if defined(__GNUC__) && !defined(DEBUG)
 #define V8_INLINE(declarator) inline __attribute__((always_inline)) declarator
 #elif defined(_MSC_VER) && !defined(DEBUG)
@@ -6558,7 +6523,6 @@ void* Context::GetAlignedPointerFromEmbedderData(int index) {
 }  // namespace v8
 
 
-#undef V8EXPORT
 #undef TYPE_CHECK