(reorder_font_vector): Fix typo.

(reorder_font_vector): Fix typo.
(fontset_find_font): Don't add a font-spec specifying a script.
Use 0 (not Qt) for the indication of empty font-group.  Change the
format of RFONT-DEF.  Return Qt if no font in the font-group
support the character.
(fontset_font): Adjusted for the above change.  If no font was
found the character, remember that.
(face_for_char): Adjusted for the change of RFONT-DEF.
(Fset_fontset_font): Allow nil for FONT-SPEC to explicitly specify
no font for the target.
(Finternal_char_font): Adjusted for the change of RFONT-DEF.