cad/freecad: attempt to fix build on CURRENT

hard cast to make call to abs unambiguous

Error was:

/wrkdirs/usr/ports/cad/freecad/work/FreeCAD-1.1.1/src/Mod/TechDraw/Gui/CommandCreateDims.cpp:1106:52: error: call to 'abs' is ambiguous
1106 | int alpha = std::round(Base::toDegrees(std::abs<float>(std::atan(type == "DistanceY" ? (dx / dy) : (dy / dx)))));