1. Remove freetype dependency:
- was not being used by build
- trying to enable freetype gives nontrivial error
'gdoTextWidth: Problem doing text layout (GDFONTPATH=)'
2. Correctly link manpages by specifying 'outputs'.
3. Separate nativeBuildInputs from buildInputs
Signed-off-by: Sirio Balmelli <sirio@b-ad.ch>