Inform the decorators where to find DoublyLinkedList.h

Prior to this, jam -q [ClassicBe|MacDecorator|WinDecorator] would fail.
They still fail, but for one less reason at least.
Add FreeType headers dependencies, #8716.

This allows MacDecorator to build once again.

Due to other errors, BeDecorator and WinDecorator do not (yet) fail on the
missing FreeType header -- hence it being only a comment for now.