[PATCH] Port libgccjit to Windows.

[Nicolas Bértolo]

> I'm going to have to trust your Windows expertise here; the tempdir
> code looks convoluted to me, but perhaps that's the only way to do it.
> (Microsoft's docs for "SECURITY_ATTRIBUTES" suggest to me that if
> lpSecurityDescriptor is NULL, then the directory gets a default
> security descriptor, and that this may mean it's only readable by the
> user represented by the access token of the process [1], which might
> suggest a simplification - but I'm very hazy on how the security model
> in Windows works)

I tested this and it gives write access to the "Authenticated Users" group.
The
way I did it gives access only to the user that owns the libgccjit process.
I
have to admit that it is a lot of code and it is hard to understand unless
you
know the security model of Windows well. I don't know it well, I wrote this
keeping the documentation close and experimenting.

> I was able to successfully bootstrap and regression test with your
> patch on x86_64-pc-linux-gnu.  I also verified that the result of "make
> install" was not affected for my configuration.

Great.

> I've pushed your patch to master as
> c83027f32d9cca84959c7d6a1e519a0129731501.
>
> Thanks again for the patch
> Dave

Thanks to you for all the good feedback.

Nico.