EDK: Remove MOJO_SYSTEM_IMPL_EXPORT, system_impl_export.h, etc.

mojo/edk/system/platform_handle_dispatcher.h

Index: mojo/edk/system/platform_handle_dispatcher.h
diff --git a/mojo/edk/system/platform_handle_dispatcher.h b/mojo/edk/system/platform_handle_dispatcher.h
index 8e8cf6904d96450fb8f6223cabcc78996155d9fe..86d63e598893999002479f8bac2ba7b99ab770fd 100644
--- a/mojo/edk/system/platform_handle_dispatcher.h
+++ b/mojo/edk/system/platform_handle_dispatcher.h
@@ -7,7 +7,6 @@
 
 #include "mojo/edk/embedder/scoped_platform_handle.h"
 #include "mojo/edk/system/simple_dispatcher.h"
-#include "mojo/edk/system/system_impl_export.h"
 #include "mojo/public/cpp/system/macros.h"
 
 namespace mojo {
@@ -15,8 +14,7 @@ namespace system {
 
 // A dispatcher that simply wraps/transports a |PlatformHandle| (only for use by
 // the embedder).
-class MOJO_SYSTEM_IMPL_EXPORT PlatformHandleDispatcher final
-    : public SimpleDispatcher {
+class PlatformHandleDispatcher final : public SimpleDispatcher {
  public:
   static scoped_refptr<PlatformHandleDispatcher> Create(
       embedder::ScopedPlatformHandle platform_handle) {