Fix compilation of xmenu.c and unexcoff.c, clean up MSDOS source files.

Fix compilation of xmenu.c and unexcoff.c, clean up MSDOS source files.

 unexcoff.c: Remove the parts used when "emacs" is not defined.
 (report_error, report_error_1): Ditto.
 (write_segment): Remove "#if 0" unused code.
 (make_hdr): Remove code that was "#ifndef NO_REMAP" before
 NO_REMAP was removed (in 2010-07-29T03:25:08Z!dann@ics.uci.edu).
 (start_of_text): Remove unused function (was used only if NO_REMAP
 was NOT defined).
 msdos.c (IT_set_face): Fix format string to match argument
 types.
 (IT_write_glyphs, IT_note_mode_line_highlight)
 (IT_set_frame_parameters): Remove unused variables.
 (x_set_menu_bar_lines): Declare set_menu_bar_lines.
 (IT_set_terminal_modes): Disambiguate expression in if clause.
 (Fmsdos_remember_default_colors): Return Qnil.
 (IT_set_frame_parameters): Add parens to disambiguate boolean
 expression for logging the cursor type to termscript.
 (keyboard_layout_list, keypad_translate_map)
 (grey_key_translate_map): Add braces in inner initializers.
 (dos_rawgetc): Add parens in condition for mouse-3 button-press.
 (dos_rawgetc): Remove unused label.
 (XMenuActivate): Add braces to remove ambiguous `else'.
 (dos_ttraw): Always return a value.
 (spawnve): Declare.
 (run_msdos_command): Cast 3rd arg of spawnve to "char **".
 dosfns.h (x_set_title): Declare.
 w16select.c (Fw16_set_clipboard_data, Fw16_get_clipboard_data):
 Remove unused variables.
 dosfns.c (Fint86, Fdos_memget, Fdos_memput): Remove unused
 variables.
 (init_dosfns): Declare get_lim_data.
 (system_process_attributes): Declare Fget_internal_run_time.
 xmenu.c (xmenu_show) [!USE_X_TOOLKIT && !USE_GTK]: Fix argument
 list to be consistent with menu.h.