/opt/FreeCAD/Mod/Part/libPart.so.2: undefined symbol: _ZNK18Standard_Transient8HashCodeEi
If you remove the name decorator then it is exactly this method Standard_Transient::HashCode().
I quickly checked the oce0.10.0 which is based on OCC6.5.3 and there is indeed no method HashCode() any more. So, it apparently means that you don't have a clean build of FreeCAD. Do a "make clean" and build everything again.