ioctl: Remove link dependency on native Windows.

ioctl: Remove link dependency on native Windows.

* lib/fd-hook.h: Renamed from lib/close-hook.h.
(gl_close_fn, gl_ioctl_fn): New types.
(struct fd_hook): Renamed from struct close_hook. Change type of
private_close_fn field. Add private_ioctl_fn field.
(close_hook_fn): Add parameter for primary close method.
(execute_close_hooks, execute_all_close_hooks): Likewise.
(ioctl_hook_fn): New type.
(execute_ioctl_hooks, execute_all_ioctl_hooks): New declarations.
(register_fd_hook): Renamed from register_close_hook. Add ioctl_hook
argument.
(unregister_fd_hook): Renamed from unregister_close_hook.
* lib/fd-hook.c: Renamed from lib/close-hook.c.
Don't include <unistd.h>.
(close): Remove undef.
(anchor): Update.
(execute_close_hooks): Add argument for primary close method.
(execute_all_close_hooks): Likewise.
(execute_ioctl_hooks, execute_all_ioctl_hooks): New functions.
(register_fd_hook): Renamed from register_close_hook. Add ioctl_hook
argument. Allow each argument to be NULL.
(unregister_fd_hook): Renamed from unregister_close_hook.
* lib/close.c (rpl_close): Pass 'close' function pointer to
execute_all_close_hooks.
* lib/ioctl.c: Include <errno.h>, fd-hook.h.
(primary_ioctl): New function.
(ioctl): Don't call ioctlsocket here. Instead, call
execute_all_ioctl_hooks.
* lib/sockets.c (close_fd_maybe_socket): Add argument for primary
close method.
(ioctl_fd_maybe_socket): New function, with code from lib/ioctl.c.
(fd_sockets_hook): Renamed from close_sockets_hook.
(gl_sockets_startup, gl_sockets_cleanup): Update.
* modules/fd-hook: Renamed from modules/close-hook. Update.
* modules/close (Depends-on): Add fd-hook, remove close-hook.
* modules/sockets (Depends-on): Likewise.
* modules/ioctl (Depends-on): Add fd-hook.
* tests/test-nonblocking.c (main): Use GNULIB_TEST_SOCKET, not
GNULIB_SOCKET.