EDK: Remove MOJO_SYSTEM_IMPL_EXPORT, system_impl_export.h, etc.

mojo/edk/system/message_pipe_endpoint.h

Index: mojo/edk/system/message_pipe_endpoint.h
diff --git a/mojo/edk/system/message_pipe_endpoint.h b/mojo/edk/system/message_pipe_endpoint.h
index c6b944c04d6b6f50bf06ab37474394c20f54cf81..c488ca3a43f5e0fd00e3d6ad8962056cb0c188ae 100644
--- a/mojo/edk/system/message_pipe_endpoint.h
+++ b/mojo/edk/system/message_pipe_endpoint.h
@@ -14,7 +14,6 @@
 #include "mojo/edk/system/dispatcher.h"
 #include "mojo/edk/system/memory.h"
 #include "mojo/edk/system/message_in_transit.h"
-#include "mojo/edk/system/system_impl_export.h"
 #include "mojo/public/c/system/message_pipe.h"
 #include "mojo/public/c/system/types.h"
 #include "mojo/public/cpp/system/macros.h"
@@ -33,7 +32,7 @@ class Awakable;
 // |MessagePipeEndpoint| also implements the functionality required by the
 // dispatcher, e.g., to read messages and to wait. Implementations of this class
 // are not thread-safe; instances are protected by |MesssagePipe|'s lock.
-class MOJO_SYSTEM_IMPL_EXPORT MessagePipeEndpoint {
+class MessagePipeEndpoint {
  public:
   virtual ~MessagePipeEndpoint() {}