Include charset.h.

Include charset.h.
(allocate_face, copy_face, face_eq1): Handle member `fontset' of
struct face, i.e. initialize, copy, and check it.
(intern_face, clear_face_cache): Handle member `non_ascii_gc' of
struct face, i.e. initialize and free it.
(free_frame_faces): Unload font only when fontset is not used.
Free non_ascii_gc.
(frame_update_line_height, merge_faces, compute_base_face): Handle
fontset.
(recompute_base_faces): Free non_ascii_gc.
(Fset_face_attribute_internal): Handle fontset.