libcpp: Update Unicode copyright years

I've noticed I forgot to update copyright years when updating from
Unicode 15.0.0 (and makeucnid.cc had it hopelessly obsolete).

2023-03-16  Jakub Jelinek  <jakub@redhat.com>

	* makeucnid.cc (write_copyright): Update Unicode copyright years
	up to 2022.
	* makeuname2c.cc (write_copyright): Likewise.
	* ucnid.h: Regenerated.
	* uname2c.h: Regenerated.