Make building under stricter warning flags somewhat cleaner.

Make building under stricter warning flags somewhat cleaner.
Flags used: -Wold-style-declaration -Wunused-function -Wstrict-prototypes

* lib-src/emacsclient.c (getcwd, w32_getenv):
* lib-src/ntlib.h (getlogin, getuid, getegid, getgid): Fix prototypes.

* nt/runemacs.c (set_user_model_id): Fix prototype.

* src/callproc.c (relocate_fd): Set inside #ifndef WINDOWSNT.
* src/dired.c (opendir, readdir): Fix prototypes.
* src/editfns.c (w32_get_internal_run_time): Fix prototypes.
* src/keyboard.c (input_available_signal): Declare inside #ifdef SIGIO.
* src/ndir.h (opendir, readdir, seekdir, closedir): Fix prototypes.
  (telldir): Remove declaration.
* src/ralloc.c (real_morecore, __morecore): Fix prototypes.
* src/sound.c (alsa_sound_perror): Declare inside #ifdef HAVE_ALSA.
* src/syssignal.h (strsignal): Fix prototype.
* src/term.c (tparam): Fix prototype.
  (term_get_fkeys_address, term_get_fkeys_kboard, term_get_fkeys_1)
  (term_get_fkeys): Set inside "#ifndef DOS_NT".
* src/vm-limit.c (check_memory_limits): Fix prototypes of real_morecore
  and __morecore.
* src/w32gui.h (XParseGeometry): Fix prototype.
* src/w32heap.h (get_data_start, get_data_end, init_heap): Fix prototypes.
* src/w32term.c (my_set_focus): Declare inside #if 0.
* src/w32term.h (x_window_to_frame, x_display_info_for_name, w32_term_init)
  (w32_fill_rect, w32_clear_window, init_crit, delete_crit, signal_quit)
  (drain_message_queue, get_next_msg, post_msg, parse_button)
  (ClipboardSequence_Proc): Fix prototypes.
  (wait_for_sync): Remove declaration.