Define V8_EXPORT to nothing for clients of v8.

This is to make sure that inline functions are only exported by
libv8.so and not also by all clients. This is the v8 version of
https://chromiumcodereview.appspot.com/10386108/

This CL depends on http://codereview.chromium.org/10310156/ landing
first.

BUG=chromium:90078

Review URL: https://chromiumcodereview.appspot.com/10399036

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11590 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

include/v8.h

@@ -62,11 +62,13 @@
 
 #else  // _WIN32
 
-// Setup for Linux shared library export. There is no need to distinguish
-// between building or using the V8 shared library, but we should not
-// export symbols when we are building a static library.
+// Setup for Linux shared library export.
 #if defined(__GNUC__) && (__GNUC__ >= 4) && defined(V8_SHARED)
+#ifdef BUILDING_V8_SHARED
 #define V8EXPORT __attribute__ ((visibility("default")))
+#else
+#define V8EXPORT
+#endif
 #else  // defined(__GNUC__) && (__GNUC__ >= 4)
 #define V8EXPORT
 #endif  // defined(__GNUC__) && (__GNUC__ >= 4)