Update metadata and rebuild bindings

[eiderdaus]

microsoft/wdkmetadata#37 introduced some Nt* APIs. They are not yet available in either of windows or windows-sys crates. I guess the updated metadata needs to be imported here and the bindings regenerated.

Particularly I'd like NtCancelIoFileEx implemented so tokio-rs/mio#1632 can be fixed.

[kennykerr]

#2573 updated the repo with the latest metadata. Please kick the tires and let me know if you experience any issues.

[eiderdaus]

Very well, I could patch my mio to use windows-sys' new NtCancelIoFileEx declaration, thanks! So once new crate versions are released here, mio's aforementioned bug can be fixed.

Though it took a little longer than expected because I had to look up a few imports that changed namespace (some from Win32 to Wdk no less), corroborating my suspicion that these namespaces are based on rather arbitrary naming decisions and no actual concept, but I digress.

[kennykerr]

Yes, my focus this year is on stabilizing metadata so that these somewhat subjective changes are a thing of the past and we can begin to stabilize.