SLIC3R_CAD=OFF now builds without SolveSpace or OCCT's ModelingAlgorithms
module, leaving the dependency set identical to upstream's, and the Design
tab's mate connector preference no longer appears in builds without the tab.
When the deps prefix and the project disagree about the option, the configure
fails naming the cause, rather than failing at link time or at first launch
on Windows. The Windows packaging step stages exactly the toolkits libslic3r
links.