Add declarations to header files.

Add declarations to header files.
* src/keyboard.h (xmalloc_widget_value, digest_single_submenu): Remove
declarations, menu.h has them.
(QCbutton, QCtoggle, QCradio, QClabel, extra_keyboard_modifiers)
(Vinput_method_function, Qinput_method_function)
(Qevent_symbol_element_mask, last_event_timestamp):
* src/dispextern.h (Voverflow_newline_into_fringe):
* src/font.h (QCantialias, Qp, syms_of_ftfont, syms_of_xfns)
(syms_of_ftxfont, syms_of_xftfont, syms_of_bdffont)
(syms_of_w32font, syms_of_nsfont):
* src/fontset.h (find_font_encoding, Qlatin):
* src/frame.h (Qtooltip, Qrun_hook_with_args, Vmenu_bar_mode)
(Vtool_bar_mode, set_frame_menubar):
* src/ftfont.h (ftfont_font_format, ftfont_get_fc_charset):
* src/xterm.h (Qx_gtk_map_stock):
* src/keymap.h (meta_prefix_char): Add declarations.

* src/lisp.h: Remove HAVE_SHM code, unused.
(QCmap, QCrehash_size, QCrehash_threshold, QCsize, QCtest)
(QCweakness, Qabove_handle, Qbackquote, Qbar, Qbelow_handle)
(Qborder, Qbottom, Qbox, Qcircular_list, Qcomma, Qcomma_at)
(Qcomma_dot, Qcursor, Qdefault, Qdown, Qend_scroll, Qeq, Qeql)
(Qequal, Qfile_exists_p, Qfont_param, Qfringe, Qfunction)
(Qfunction_documentation, Qhandle, Qhbar, Qheader_line, Qhollow)
(Qidentity, Qleft_margin, Qmenu, Qmenu_bar_update_hook)
(Qmode_line_inactive, Qmouse, Qoverriding_local_map)
(Qoverriding_terminal_local_map, Qratio, Qregion, Qright_margin)
(Qscroll_bar, Qtool_bar, Qtop, Qup, Qvertical_border, Qwhen)
(Qwindow_scroll_functions, Vafter_load_alist)
(Vauto_save_list_file_name, Vface_alternative_font_family_alist)
(Vface_alternative_font_registry_alist, Vface_font_rescale_alist)
(Vface_ignored_fonts, Vinhibit_redisplay, Vminibuffer_list)
(Vprint_length, Vprint_level, Vscalable_fonts_allowed)
(Vshell_file_name, Vsystem_name, Vwindow_scroll_functions)
(Vwindow_system_version, Vx_no_window_manager, initial_argc)
(initial_argv, last_nonmenu_event, load_in_progress)
(noninteractive_need_newline, scroll_margin): Add declarations.