MSVC slight version change

[mwichmann]

It seems Microsoft is "breaking" a versioning scheme that we had been assuming. Our current assumption can be seen in https://scons.org/doc/production/HTML/scons-man.html#cv-MSVC_VERSION, which is that the v143 build tools series is described by toolset version 14.3x (and Visual Studio 17.x - single digit). However, the next release will be 14.40 (for vs 17.10), which will not map to v144 build tools, but remain at v143. A blog post described this, acknowledging that there are likely to be a few issues externally:

https://devblogs.microsoft.com/cppblog/msvc-toolset-minor-version-number-14-40-in-vs-2022-v17-10/

Of course the table in the manpage can be updated, but it's the mapping in the SCons Tool that needs to be looked at.