Add make_vector and make_nil_vector

Add make_vector and make_nil_vector

This makes the callers a bit easier to read, and doubtless
improves efficiency very slightly.  It also simplifies
possible future changes to allow bignum indexes to buffers.
* src/alloc.c (allocate_vectorlike):
Prefer ptrdiff_t to size_t when either will do.
(make_vector): New function.
(Fmake_vector): Use it.
* src/buffer.c (syms_of_buffer):
* src/bytecode.c (syms_of_bytecode):
* src/category.c (Fmake_category_table, init_category_once):
* src/ccl.c (syms_of_ccl):
* src/character.c (syms_of_character):
* src/charset.c (Fdefine_charset_internal)
(Ffind_charset_region, Ffind_charset_string):
* src/chartab.c (copy_char_table):
* src/coding.c (Fdefine_coding_system_internal, syms_of_coding):
* src/composite.c (get_composition_id, Fcomposition_get_gstring):
* src/composite.h (LGLYPH_NEW):
* src/fns.c (concat, Flocale_info, make_hash_table):
* src/font.c (font_otf_ValueRecord, font_otf_anchor)
(build_style_table, syms_of_font):
* src/fontset.c (RFONT_DEF_NEW, fontset_find_font)
(dump_fontset, syms_of_fontset):
* src/image.c (xpm_make_color_table_v):
* src/keyboard.c (modify_event_symbol, menu_bar_items)
(parse_menu_item, parse_tool_bar_item, init_tool_bar_items)
(syms_of_keyboard):
* src/keymap.c (Fdefine_key, describe_map, describe_vector):
* src/lread.c (read_vector):
* src/macfont.m (macfont_shape):
* src/menu.c (init_menu_items):
* src/nsfns.m (ns_make_monitor_attribute_list):
* src/process.c (conv_sockaddr_to_lisp, network_interface_info):
* src/profiler.c (make_log):
* src/window.c (Fcurrent_window_configuration):
* src/xdisp.c (with_echo_area_buffer_unwind_data)
(format_mode_line_unwind_data):
* src/xfaces.c (Finternal_make_lisp_face)
(Fface_attributes_as_vector):
* src/xfns.c (x_make_monitor_attribute_list)
(Fx_display_monitor_attributes_list):
* src/xfont.c (syms_of_xfont):
* src/xselect.c (x_handle_dnd_message):
* src/xwidget.c (save_script_callback):
Prefer make_nil_vector (N) to Fmake_vector (make_fixnum (N), Qnil).
* src/callint.c (Fcall_interactively):
* src/charset.c (load_charset_map):
* src/chartab.c (Fmake_char_table, uniprop_encode_value_numeric):
* src/composite.c (get_composition_id)
* src/dispnew.c (Fframe_or_buffer_changed_p)
(syms_of_display):
* src/fns.c (make_hash_table, maybe_resize_hash_table):
* src/font.c (font_style_to_value):
* src/fontset.c (FONTSET_ADD, fontset_add):
* src/json.c (json_to_lisp):
* src/keymap.c (syms_of_keymap):
* src/lread.c (init_obarray):
* src/profiler.c (make_log, Fprofiler_cpu_log):
* src/term.c (term_get_fkeys_1):
Prefer make_vector (N, V) to Fmake_vector (make_fixnum (N), V).
* src/font.c (build_style_table):
* src/macfont.m (macfont_shape):
* src/process.c (conv_sockaddr_to_lisp, network_interface_info):
Prefer make_uninit_vector if the vector will be initialized soon.
* src/lisp.h (make_nil_vector): New function.