Fix building libs with Visual Studio 16.7

[chalcolith]

Visual Studio 16.7 introduced a change in C++20 compatibility that breaks building LLVM on Windows (#3634). This change adds a patch for LLVM that fixes the issue. Fixes #3634.

The change also introduces a check in CMake of the hashes of the patch files. Since the build caches in CI depend on the contents of libs/CMakeLists.txt, and that file contains the desired hash, changing the patches (and thus the desired hash) will force a rebuild of the libs build caches (in the same way as changing the Git checkout for LLVM will force a rebuild).

[ponylang-main]

Hi @kulibali,

The changelog - fixed label was added to this pull request; all PRs with a changelog label need to have release notes included as part of the PR. If you haven't added release notes already, please do.

Release notes are added by creating a uniquely named file in the .release-notes directory. We suggest you call the file 3635.md to match the number of this pull request.

The basic format of the release notes (using markdown) should be:

## Title

End user description of changes, why it's important,
problems it solves etc.

If a breaking change, make sure to include 1 or more
examples what code would look like prior to this change
and how to update it to work after this change.

Thanks.

[SeanTAllen]

Thanks @kulibali.