Revert "Merge branch 'tm_convex_intersect_rotcalip'"

This reverts commit 627d8bcaef, reversing
changes made to 66d4462724.

The change breaks build on mac

src/libslic3r/Geometry.hpp

@@ -532,8 +532,6 @@ inline bool is_rotation_ninety_degrees(const Vec3d &rotation)
     return is_rotation_ninety_degrees(rotation.x()) && is_rotation_ninety_degrees(rotation.y()) && is_rotation_ninety_degrees(rotation.z());
 }
 
-bool intersects(const Polygon &convex_poly1, const Polygon &convex_poly2);
-
 } } // namespace Slicer::Geometry
 
 #endif