Copyright years update in etags test suite

[Eli Zaretskii]

The wholesale changes of Copyright years modified the test files in
the etags test suite, and thus all the tests started to fail.

I fixed this, but I wonder whether we really need to do these updates
in the etags test suite.  The source files there are not maintained in
any way, so perhaps they could be skipped?

If we do have to update the Copyright there, then the annual update
procedure should include the corresponding update to the
expected-results files.