Split mojo_system dylib into public and private

mojo/system/memory.h

Index: mojo/system/memory.h
diff --git a/mojo/system/memory.h b/mojo/system/memory.h
index 963974abf9cb72b66b33fab0b2c33424b87d3d3d..6483e0331af9a3431a3b78087bbc5a3fdba83109 100644
--- a/mojo/system/memory.h
+++ b/mojo/system/memory.h
@@ -7,7 +7,7 @@
 
 #include <stddef.h>
 
-#include "mojo/public/system/system_export.h"
+#include "mojo/system/system_impl_export.h"
 
 namespace mojo {
 namespace system {
@@ -16,8 +16,8 @@ namespace system {
 // instantiations in the .cc file. This is used by |VerifyUserPointer<T>()|
 // below, and you should use that instead.
 template <size_t size>
-bool MOJO_SYSTEM_EXPORT VerifyUserPointerForSize(const void* pointer,
-                                                 size_t count);
+bool MOJO_SYSTEM_IMPL_EXPORT VerifyUserPointerForSize(const void* pointer,
+                                                      size_t count);
 
 // Verify that |count * sizeof(T)| bytes can be read from the user |pointer|
 // insofar as possible/necessary (note: this is done carefully since |count *