EDK: Remove MOJO_SYSTEM_IMPL_EXPORT, system_impl_export.h, etc.

mojo/edk/embedder/simple_platform_support.h

Index: mojo/edk/embedder/simple_platform_support.h
diff --git a/mojo/edk/embedder/simple_platform_support.h b/mojo/edk/embedder/simple_platform_support.h
index 0cc888d9c06ce2b019fa73a42735564ee80ef2e8..19c56a3a65af2259881816633d50fdda1e512238 100644
--- a/mojo/edk/embedder/simple_platform_support.h
+++ b/mojo/edk/embedder/simple_platform_support.h
@@ -6,7 +6,6 @@
 #define MOJO_EDK_EMBEDDER_SIMPLE_PLATFORM_SUPPORT_H_
 
 #include "mojo/edk/embedder/platform_support.h"
-#include "mojo/edk/system/system_impl_export.h"
 #include "mojo/public/cpp/system/macros.h"
 
 namespace mojo {
@@ -17,8 +16,7 @@ namespace embedder {
 // has no state, and different instances of |SimplePlatformSupport| are mutually
 // compatible (i.e., you don't need to use a single instance of it everywhere --
 // you may simply create one whenever/wherever you need it).
-class MOJO_SYSTEM_IMPL_EXPORT SimplePlatformSupport final
-    : public PlatformSupport {
+class SimplePlatformSupport final : public PlatformSupport {
  public:
   SimplePlatformSupport() {}
   ~SimplePlatformSupport() override {}