Oh I just have followed the solution Ignacio Vazquez-Abrams has suggest which is install tk-dev before building the python. (Building the Python-3.6.1 from source on Ubuntu 16.04.)
There was pre-compiled objects and binaries I have had build yesterday though, I didn't clean up the objects and just build again on the same build path. And it works beautifully.
sudo apt install tk-dev
(On the python build path)
(No need to conduct 'make clean')
./configure
make
sudo make install
That's it!