No functional change, this adds LIB definition and args to cmake files.
Without this it's difficult to migrate away from 'BLENDER_SORTED_LIBS'
since there are many platforms/configurations that could break when
changing linking order.
Manually add and enable WITHOUT_SORTED_LIBS to try building
without sorted libs (currently fails since all variables are empty).
This check will eventually be removed.
See T46725.
Draco is added as a library under extern/ and builds a shared library that is
installed into the Python site-packages. This is then loaded by the glTF add-on
to do mesh compression.
Differential Revision: https://developer.blender.org/D4501