Build only the OCCT and solver pieces the Design tab needs

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.

src/libslic3r/AppConfig.cpp

@@ -310,12 +310,14 @@ void AppConfig::set_defaults()
     if (get("zoom_to_mouse").empty())
         set_bool("zoom_to_mouse", false);
 
+#ifdef SLIC3R_CAD
     // Design tab: draw a mate connector as a face rather than as the abstract disc + roll
     // quadrant. Defaults ON — face orientation is hardwired perception, so the roll and the
     // verse read without being learned, which no abstract glyph achieves. Turning it off
     // restores the conventional CAD representation for users who expect it (snaporca-x0kd).
     if (get("design_connector_face_glyph").empty())
         set_bool("design_connector_face_glyph", true);
+#endif
 
 //#ifdef SUPPORT_SHOW_HINTS
     if (get("show_hints").empty())