Fix d8 build error when V8_SHARED is unset on Linux.

TBR=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/21053002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15927 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/d8.cc

@@ -68,7 +68,7 @@
 #include "v8.h"
 #endif  // V8_SHARED
 
-#if V8_OS_UNIX
+#if !defined(_WIN32) && !defined(_WIN64)
 #include <unistd.h>  // NOLINT
 #endif