* font.c, fontset.c: Make symbols static if they're not exported.

* font.c, fontset.c: Make symbols static if they're not exported.

* dispextern.h (FACE_SUITABLE_FOR_ASCII_CHAR_P): New macro.
(FACE_SUITABLE_FOR_CHAR_P): Use it.
* font.c (font_close_object): Now static.
* font.h (font_close_object): Remove.
* fontset.c (FONTSET_OBJLIST): Remove.
(free_realized_fontset) #if-0 the body, which does nothing.
(face_suitable_for_char_p): #if-0, as it's never called.
* fontset.h (face_suitable_for_char_p): Remove decl.
* xfaces.c (face_at_string_position): Use
FACE_SUITABLE_FOR_ASCII_CHAR_P, not FACE_SUITABLE_FOR_CHAR_P,
since 0 is always ASCII.