More panic info on failure of Windows rand

[ChrisDenton]

Add the error messages of both BCryptGenRandom and RtlGenRandom in the (unlikely) event they both fail. Ideally I'd love to print diagnostic information if only BCryptGenRandom fails but that's not really possible here.

Also use an isize for the algorithm handle instead of a pointer. This matches the windows_sys crate and I think it doesn't make sense to pretend they're pointers when we don't (and won't) use them as such. But I can undo that change if it's a bridge too far.

r? @thomcc

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[thomcc]

I think it doesn't make sense to pretend they're pointers when we don't (and won't) use them as such. But I can undo that change if it's a bridge too far.

I think windows-sys goes way too far with is (since it uses isize even if the API sometimes returns pointers), but for this I don't mind. I will admit this is more verbose than I'd like to be, but it has been quite a pain and its not like panic strings are stable.

@bors r+

[bors]

📌 Commit 884f945 has been approved by thomcc

It is now in the queue for this repository.

[ChrisDenton]

@bors r-

[ChrisDenton]

I'm closing this and replacing with a PR that fixes a problem on WINE.