removed unnecessary clear() when calling set_mesh

Former-commit-id: d438c8e1538eb47c4a7cf8d5e6b8602515b4a450

include/igl/viewer/ViewerData.cpp

@@ -79,7 +79,6 @@ IGL_INLINE void igl::ViewerData::set_mesh(const Eigen::MatrixXd& _V, const Eigen
 
   if (V.rows() == 0 && F.rows() == 0)
   {
-    clear();
     V = V_temp;
     F = _F;