* Fix several issues with the Halide port after v12
1. Use vcpkg-cmake and vcpkg-cmake-config ports
2. Fix usage file to point to relevant documentation
3. Remove OpenGL feature (Halide 12 dropped support)
4. Drop VCPKG_POLICY_EMPTY_PACKAGE
5. Set new Halide packaging variables for better vcpkg compliance.
* update versions
* [llvm] update to 12.0.0, enable zlib and libxml2
* [llvm] disable libxml2 by default, arm64-windows should be supported
* [llvm] try to fix build with ffi on Windows #17663
* [llvm] re-enable libxml2
* [llvm] fix formatting
* [llvm] overwrite version
* [mesa] update to v21.1.0
* [llvm] update ci.baseline
* [halide] update to the latest master commit
* [llvm] disable libxml2 port until complete PR #15390
* update versions
* [llvm] fix disabling of external libraries
* update version
* update ci.baseline
* update ci.baseline
* fix typo
* [llvm] fix libxml2 (depends on #17945)
* revert "[halide] update to the latest master commit"
* update versions
* [halide] fix zlib dependency for tools
* update versions
* [halide] update to official release v12.0.0
* update versions
* [halide] update to v12.0.1
* update version
* [mesa] remove llvm from defaults
* update version
* update ci.baseline
* [mesa] update to v21.1.2 and fix build with LLVM on Windows
* [llvm] allow to build libunwind project on Windows
* update versions
* [mesa] update ci.baseline.txt to disable x64-windows-static-md, may be fixed in the PR #18495
