[PATCH] ntdll: Add support for FileReplaceCompletionInformation

[Zebediah Figura]

Hello Andrew, thanks for the patch!

Could you please add tests for this functionality, to prove its 
correctness and protect against future regressions?

I also have one suggestion on the implementation: instead of adding a 
new server request, perhaps it would make more sense to add a "replace" 
parameter to the existing set_completion_info request, and thus have a 
smaller diff to the server interface.