Previously this was adding it in to all file opens which was causing
inefficiencies under Windows where it stats the file using
open/fstat/close.
This change will make stat operations run much quicker under Windows
as they won't have to open the underlying file
This problem was introduced in61b6159a05336bd7ba105766de2d2ff171f7fb81
where we added O_CREATE to all file opens and creates.