[llvm] [libcxx] [libc++] Format the code base (PR #74334)

[Petr Hosek via llvm-commits]

petrhosek wrote:

> @petrhosek Thanks, I just did [de5c49f](https://github.com/llvm/llvm-project/commit/de5c49f7e63f3237afe1e647d359cb8a5227ba4d) to try and make the build green again. Let me know if you still see issues.

Thanks @ldionne, that resolved the issue.

I looked into solutions, and the only two options I found are to either disable Clang-Format:
```
// clang-format off
#include <windows.h>
#include <process.h>
// clang-format on
```
or to move `<windows.h>` into a separate group:
```
#include <windows.h>

#include <process.h>
```

https://github.com/llvm/llvm-project/pull/74334