wget: upgrade 1.21.3 -> 1.21.4

Stable version release

Noteworthy changes in release 1.21.4 (2023-05-11)

** Document --retry-on-host-error in help text

** Increase read buffer size to 64k. This should speed up downloads on gigabit
and faster connections

** Update deprecated option '--html-extension' to '--adjust-extension' in
documentation

** Update gnulib compatibility layer.
   Fixes HSTS test failures on i686. (Thanks to Andreas Enge for ponting it out)

License-Update: copyright years

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 67ec2d5b)
Signed-off-by: Steve Sakoman <steve@sakoman.com>