doc: Update for other functions added in POSIX:2024.
* doc/posix-functions/be16toh.texi: New file.
* doc/posix-functions/be32toh.texi: New file.
* doc/posix-functions/be64toh.texi: New file.
* doc/posix-functions/dcgettext_l.texi: New file.
* doc/posix-functions/dcngettext_l.texi: New file.
* doc/posix-functions/dgettext_l.texi: New file.
* doc/posix-functions/dngettext_l.texi: New file.
* doc/posix-functions/getlocalename_l.texi: New file.
* doc/posix-functions/gettext_l.texi: New file.
* doc/posix-functions/htobe16.texi: New file.
* doc/posix-functions/htobe32.texi: New file.
* doc/posix-functions/htobe64.texi: New file.
* doc/posix-functions/htole16.texi: New file.
* doc/posix-functions/htole32.texi: New file.
* doc/posix-functions/htole64.texi: New file.
* doc/posix-functions/le16toh.texi: New file.
* doc/posix-functions/le32toh.texi: New file.
* doc/posix-functions/le64toh.texi: New file.
* doc/posix-functions/ngettext_l.texi: New file.
* doc/posix-functions/posix_close.texi: New file.
* doc/posix-functions/posix_devctl.texi: New file.
* doc/posix-functions/posix_getdents.texi: New file.
* doc/posix-functions/posix_spawn_file_actions_addchdir.texi: New file.
* doc/posix-functions/posix_spawn_file_actions_addfchdir.texi: New file.
* doc/posix-functions/sig2str.texi: New file.
* doc/posix-functions/str2sig.texi: New file.
* doc/posix-functions/tcgetwinsize.texi: New file.
* doc/posix-functions/tcsetwinsize.texi: New file.
* doc/posix-functions/wcslcat.texi: New file.
* doc/posix-functions/wcslcpy.texi: New file.
* doc/gnulib.texi (Functions in <devctl.h>, Functions in <endian.h>):
New sections.
(Functions in <dirent.h>, Functions in <libintl.h>,
Functions in <locale.h>, Functions in <signal.h>,
Functions in <spawn.h>, Functions in <termios.h>,
Functions in <unistd.h>, Functions in <wchar.h>): Include the other new
files.
* doc/posix-functions/strlcat.texi: Update.
* doc/posix-functions/strlcpy.texi: Update.