At the beginning we only checked for the vtk library as a whole without checking for specific components. This caused problems (on Debian) when the vtk component for the GUI binding is linked against Qt5 while FreeCAD is built against Qt4.
To solve this issue we started to check for only certain components. This however lead to build errors of smesh because the include path didn't include the hdf5 stuff any more. The problem is that on some platforms vtkIOMPIParallel, vtkParallelMPI or vtkhdf5 is required while on other platform these components do not even exist.
So, to solve this problem it is checked if a corresponding cmake file exists and if yes the module is appended.
Now the new problem is that you had installed vtk6 and 7. FreeCAD is supposed to link against vtk7 but the above mechanism finds the cmake files of vtk6 which don't exist for vtk7 any more.
Now it's possible to check this list if a module is available instead of directly checking path names. Can you try if you replace the corresponding block in the cmake file with:
CMakeFiles/FemGui.dir/TaskPostBoxes.cpp.o: In function `vtkRenderingCore_AutoInit::~vtkRenderingCore_AutoInit()':
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkInteractionStyle_AutoInit_Destruct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingFreeType_AutoInit_Destruct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingOpenGL_AutoInit_Destruct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingOpenGL2_AutoInit_Destruct()'
CMakeFiles/FemGui.dir/TaskPostBoxes.cpp.o: In function `vtkRenderingCore_AutoInit':
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkInteractionStyle_AutoInit_Construct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingFreeType_AutoInit_Construct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingOpenGL_AutoInit_Construct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingOpenGL2_AutoInit_Construct()'
CMakeFiles/FemGui.dir/AppFemGui.cpp.o: In function `vtkRenderingCore_AutoInit':
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkInteractionStyle_AutoInit_Construct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingFreeType_AutoInit_Construct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingOpenGL_AutoInit_Construct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingOpenGL2_AutoInit_Construct()'
CMakeFiles/FemGui.dir/ViewProviderFemPostObject.cpp.o: In function `vtkRenderingCore_AutoInit':
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkInteractionStyle_AutoInit_Construct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingFreeType_AutoInit_Construct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingOpenGL_AutoInit_Construct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingOpenGL2_AutoInit_Construct()'
CMakeFiles/FemGui.dir/ViewProviderFemPostPipeline.cpp.o: In function `vtkRenderingCore_AutoInit':
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkInteractionStyle_AutoInit_Construct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingFreeType_AutoInit_Construct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingOpenGL_AutoInit_Construct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingOpenGL2_AutoInit_Construct()'
CMakeFiles/FemGui.dir/ViewProviderFemPostFilter.cpp.o: In function `vtkRenderingCore_AutoInit':
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkInteractionStyle_AutoInit_Construct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingFreeType_AutoInit_Construct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingOpenGL_AutoInit_Construct()'
/usr/local/include/vtk-7.0/vtkRenderingCoreModule.h:41: undefined reference to `vtkRenderingOpenGL2_AutoInit_Construct()'
collect2: error: ld returned 1 exit status
src/Mod/Fem/Gui/CMakeFiles/FemGui.dir/build.make:2317: recipe for target 'Mod/Fem/FemGui.so' failed
make[2]: *** [Mod/Fem/FemGui.so] Error 1
CMakeFiles/Makefile2:3631: recipe for target 'src/Mod/Fem/Gui/CMakeFiles/FemGui.dir/all' failed
make[1]: *** [src/Mod/Fem/Gui/CMakeFiles/FemGui.dir/all] Error 2