Omit some unnecessary casts.

Omit some unnecessary casts.

Many of these go back to the old pre-C89 days, when they may have
been needed, but we've been assuming C89 or later for a while now.
* alloc.c (live_string_p, live_cons_p, live_symbol_p)
(live_float_p, live_misc_p, live_vector_p):
* buffer.c (compare_overlays, cmp_for_strings, mmap_find)
(mmap_alloc, alloc_buffer_text, enlarge_buffer_text)
(defvar_per_buffer):
* callint.c (Fcall_interactively):
* doc.c (Fsubstitute_command_keys):
* filelock.c (get_boot_time):
* frame.c (xrdb_get_resource):
* gtkutil.c (hierarchy_ch_cb, qttip_cb, style_changed_cb)
(delete_cb, xg_dialog_response_cb, xg_maybe_add_timer)
(xg_get_file_name_from_selector, menuitem_destroy_callback)
(menuitem_highlight_callback, menu_destroy_callback)
(xg_update_menu_item, xg_modify_menubar_widgets, menubar_map_cb)
(xg_tool_bar_callback, xg_get_tool_bar_widgets)
(xg_tool_bar_detach_callback, xg_tool_bar_attach_callback)
(xg_tool_bar_help_callback, tb_size_cb):
* image.c (xpm_alloc_color, png_read_from_memory)
(png_read_from_file, png_load_body, our_memory_skip_input_data)
(jpeg_memory_src, jpeg_file_src, imagemagick_load_image)
(syms_of_image):
* keymap.c (describe_map):
* nsfns.m (Fns_display_monitor_attributes_list):
* nsmenu.m (process_dialog:):
* nsterm.m (hold_event):
* process.c (wait_reading_process_output):
* regex.c (REGEX_REALLOCATE, re_set_registers, re_exec, regexec):
* scroll.c (do_direct_scrolling, scrolling_1):
* termcap.c (tgetent):
* window.c (check_window_containing, add_window_to_list)
(freeze_window_starts):
* xdisp.c (compare_overlay_entries, vmessage):
* xfns.c (x_window, x_get_monitor_attributes_xinerama)
(x_get_monitor_attributes_xrandr)
(Fx_display_monitor_attributes_list, x_display_info_for_name)
(Fx_open_connection, file_dialog_cb, file_dialog_unmap_cb):
* xfont.c (xfont_match, xfont_open):
* xmenu.c (x_menu_wait_for_event, menu_highlight_callback)
(menubar_selection_callback, menu_position_func)
(popup_selection_callback, create_and_show_popup_menu)
(dialog_selection_callback, create_and_show_dialog):
* xrdb.c (x_get_string_resource):
(main) [TESTRM]:
* xsmfns.c (x_session_check_input):
* xterm.c (x_draw_glyphless_glyph_string_foreground)
(xm_scroll_callback, xg_scroll_callback, xg_end_scroll_callback)
(xaw_jump_callback, xaw_scroll_callback):
Omit unnecessary casts.