Add support for MSVC 1940 version (14.4)
MSVC 1940 (14.4) is now deployed by microsoft: https://devblogs.microsoft.com/cppblog/msvc-toolset-minor-version-number-14-40-in-vs-2022-v17-10/
This adds support for it in xz and boost.
Regarding boost, a fix upstream is needed, which is provided as a patch for now: https://github.com/boostorg/boost/issues/914
Edited by Mathieu Westphal (Kitware)