Convert some more functions to standard C.

Convert some more functions to standard C.

* lib-src/emacsclient.c (get_current_dir_name, w32_get_resource)
  (w32_getenv, w32_set_user_model_id, w32_window_app, w32_execvp)
  (close_winsock, initialize_sockets, w32_find_emacs_process)
  (w32_give_focus):
* lib-src/ntlib.c (getlogin, getuid, getgid, getegid):
* nt/addpm.c (add_registry, main):
* nt/cmdproxy.c (get_env_size):
* nt/ddeclient.c (main):
* nt/runemacs.c (set_user_model_id):
* src/alloc.c (emacs_blocked_free, emacs_blocked_malloc)
  (emacs_blocked_realloc, uninterrupt_malloc):
* src/fringe.c (w32_reset_fringes):
* src/image.c (convert_mono_to_color_image, lookup_rgb_color)
  (init_color_table, XPutPixel, jpeg_resync_to_restart_wrapper):
* src/sound.c (be2hs, do_play_sound):
* src/vm-limit.c (get_lim_data, ret_lim_data):
* src/w32term.c (x_free_frame_resources):
* src/xfaces.c (x_create_gc, x_free_gc):
  Convert definitions to standard C.