Unify mouse highlight code of MSDOS and GUI sessions.

Unify mouse highlight code of MSDOS and GUI sessions.

 xdisp.c (coords_in_mouse_face_p): Move prototype out of the
 HAVE_WINDOW_SYSTEM conditional.
 (x_y_to_hpos_vpos, frame_to_window_pixel_xy): Move out of the
 HAVE_WINDOW_SYSTEM block.
 (try_window_id) [HAVE_GPM || MSDOS]: Call
 x_clear_window_mouse_face.
 (draw_row_with_mouse_face): Implementation for HAVE_WINDOW_SYSTEM
 systems.
 (show_mouse_face): Call it, instead of calling draw_glyphs directly.
 (show_mouse_face, clear_mouse_face, coords_in_mouse_face_p)
 (cursor_in_mouse_face_p, rows_from_pos_range)
 (mouse_face_from_buffer_pos, mouse_face_from_string_pos)
 (note_mode_line_or_margin_highlight, note_mouse_highlight)
 (x_clear_window_mouse_face, cancel_mouse_face): Move out of the
 HAVE_WINDOW_SYSTEM block.  Ifdef away window-system specific
 fragments.
 (note_mouse_highlight): Call popup_activated for MSDOS as well.
 Clear mouse highlight if pointer is over glyphs whose OBJECT is an
 integer.
 (mouse_face_from_buffer_pos): Add parentheses around && within ||.
 xmenu.c (popup_activated): Don't define on MSDOS.
 dispnew.c (mirror_make_current): Set Y coordinate of the
 mode-line and header-line rows.
 termchar.h (struct tty_display_info): Define mouse_face_*
 members not only for MSDOS.  Delete stray whitespace.
 <mouse_face_beg_x, mouse_face_beg_y, mouse_face_overlay>: New
 struct members.
 dispextern.h (DPYINFO_DEFINED) [HAVE_X_WINDOWS]: Define.
 (DPYINFO_DEFINED) [HAVE_NTGUI]: Define.
 (DPYINFO_DEFINED) [HAVE_NS]: Define.
 (Display_Info) [!DPYINFO_DEFINED]: Define here.
 (FRAME_X_DISPLAY_INFO) [HAVE_GPM]: Define.
 (FRAME_X_DISPLAY_INFO): Define to NULL if not defined.
 (frame_to_window_pixel_xy, note_mouse_highlight)
 (x_clear_window_mouse_face, cancel_mouse_face, clear_mouse_face)
 (show_mouse_face, cursor_in_mouse_face_p): Move prototypes out of
 HAVE_WINDOW_SYSTEM conditional.
 (draw_row_with_mouse_face): Declare prototype.
 msdos.h (Display_Info): Don't define here.
 msdos.c (show_mouse_face, clear_mouse_face)
 (fast_find_position, IT_note_mode_line_highlight)
 (IT_note_mouse_highlight): Functions deleted.
 (IT_frame_up_to_date, dos_rawgetc): Call note_mouse_highlight
 instead of IT_note_mouse_highlight.
 (draw_row_with_mouse_face, popup_activated): New functions.