python3: package tkinter's shared objects

python3: package tkinter's shared objects

Seems every time python is updated this gets removed. That's likely
because the tk option can't be enabled in python3-native without
creating a dependency loop.

Instead of manually editing the manifest every time, explicitly
add it in the recipe as suggested by Alexander Kanavin.

Signed-off-by: Dan McGregor <dan.mcgregor@usask.ca>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>