current_perdisplay, all_perdisplays, Lisp_Misc_Display_Objfwd,
Lisp_Display_Objfwd, XDISPLAY_OBJFWD, DISPLAY_OBJFWDP,
GC_DISPLAY_OBJFWDP, display_locked, the_only_perdisplay,
DEFVAR_DISPLAY. All uses changed.
(struct KBOARD): New member reference_count.
(initial_kboard): Declare this var.
current_perdisplay, all_perdisplays, Lisp_Misc_Display_Objfwd,
Lisp_Display_Objfwd, XDISPLAY_OBJFWD, DISPLAY_OBJFWDP,
GC_DISPLAY_OBJFWDP, display_locked, the_only_perdisplay,
DEFVAR_DISPLAY. All uses changed.
(struct KBOARD): New member reference_count.
(initial_kboard): Declare this var.