Allow disabiling freetype in TKService

First of all : I'm not sure if this is of interest of the whole OCE users, or if I'd better keep this patch private.
This branch avoids freetype usage in this specific scenario:
Kernel + OCAF + DataExchange but no Visualization.
The freetype dependency is useless in this case (apart certain font constants).

DISABLE_X11 was not enough since it disables OCAF (as it requires TKService and V3d)