pango/src/color.hg: Fix call to _CLASS_BOXEDTYPE_STATIC
pango/src/color.hg: Fix call to _CLASS_BOXEDTYPE_STATIC

Remove all the parameters after the second one, they were originally ignored
as _CLASS_BOXEDTYPE_STATIC accepted 2 arguments and will cause issues with
the new api_decoration stuff that was recently added to glibmm, which was the
third argument

GNOME/pangomm,GNOME/pangomm,GNOME/pangomm,GNOME/pangomm