gtkLibs224.gtk actually propagates libpng etc. through gdk_pixbuf,
so using gtk.libpng etc. makes no sense.
Remove unused 'inherit lib*;' in gtk.
svn path=/nixpkgs/trunk/; revision=29383
It looks like building and installing. Part of the expression I copied from wxGTK 2.8,
and some parts of it may be irrelevant or wrong.
svn path=/nixpkgs/trunk/; revision=26484