Windows Build Failing for kdiff3

[Michael Reeves]

https://build.kde.org/job/Extragear/job/kdiff3/job/kf5-qt5%20WindowsMSVCQt5.15/

KDiff3 requires boost-headers 1.71.0 or later due to an MSVC specific
link time bug See https://github.com/boostorg/safe_numerics/issues/71.
Craft however is refusing to take the updated configuration files into
account and instead uses 1.69.0. All settings that I am aware of have
been updated.