(Qbitmap_spec_p): Replaces Qpixmap_spec_p.

(Qbitmap_spec_p): Replaces Qpixmap_spec_p.
(Fbitmap_spec_p): Replaces Fpixmap_spec_p.
(load_pixmap): Use Fbitmap_spec_p and Qbitmap_spec_p instead of
Fpixmap_spec_p and Qpixmap_spec_p.
(load_face_colors, check_lface_attrs,
merge_face_vector_with_property,
Finternal_set_lisp_face_attribute): Use Fbitmap_spec_p.
(syms_of_xfaces): Initialize Qbitmap_spec_p, defsubr
Fbitmap_spec_p.