* lisp.h (Mouse_HLInfo): Remove set-but-unused mouse_face_image_state

* lisp.h (Mouse_HLInfo): Remove set-but-unused mouse_face_image_state
member.  Adjust users.  Convert mouse_face_past_end, mouse_face_defer
and mouse_face_hidden members to a bitfields.
* frame.h (struct frame): Remove set-but-not-used space_width member.
(FRAME_SPACE_WIDTH): Remove.
* nsterm.m, w32term.c, xterm.c: Adjust users.
* termchar.h (struct tty_display_info): Remove set-but-unused se_is_so
member.  Adjust users.  Convert term_initted, delete_in_insert_mode,
costs_set, insert_mode, standout_mode, cursor_hidden and flow_control
members to a bitfields.