contrib: Partial fix for failed update-copyright --this year [PR108413]

contrib: Partial fix for failed update-copyright --this year [PR108413]

As mentioned on IRC or in PR108413, the last update-copyright.py --this year
failed and that is why we are in a strange state where some copyrights have
been updated and others have not.
The full list of errors I got was I think:
gcc/m2/mc-boot/GmcOptions.c: unrecognised copyright: comment (f, (const char *) "Copyright (C) ''2021'' Free Software Foundation, Inc.", 53);
gcc/m2/mc-boot/GmcOptions.c: unrecognised copyright: comment (f, (const char *) "Copyright (C) ''2021'' Free Software Foundation, Inc.", 53);
gcc/testsuite/gm2/switches/pedantic-params/pass/Strings.mod: unrecognised copyright holder: Faculty of Information Technology,
gcc/testsuite/gm2/switches/pedantic-params/pass/Strings2.mod: unrecognised copyright holder: Faculty of Information Technology,
libphobos/libdruntime/__builtins.di: unrecognised copyright: * Copyright: Copyright Digital Mars 2022
libstdc++-v3/src/c++17/fast_float/fast_float.h: unrecognised copyright holder: The fast_float authors
libstdc++-v3/include/c_compatibility/stdatomic.h: unrecognised copyright holder: The GCC developers

The following patch deals with the gcc/testsuite/gm2 ones and
with the fast_float.h one, ok for trunk?

Not really sure what we should do in the GmcOptions.c case
(perhaps obfuscate it in the source somehow by splitting
the string literals into different substrings
Perhaps "Copy" "right (" "C) ''..." would do it?  Or do we want
to bump there each year (manually or by the script)?
E.g. in gcc.cc we have
      printf ("Copyright %s 2023 Free Software Foundation, Inc.\n",
              _("(C)"));
which also prints (C) nicer in Unicode if possible and is updated
by hand each year.

I have no idea about the libphobos case, we have tons of
libphobos/src/std/format/spec.d:Copyright: Copyright The D Language Foundation 2000-2013.
libphobos/src/std/random.d:Copyright: Copyright Andrei Alexandrescu 2008 - 2009, Joseph Rushton Wakeling 2012.
etc. lines and those aren't reported as errors.

And the last one is that I think for The GCC developers we should treat it
similarly like FSF and bump copyright on it.
Would
        canon_gcc = 'The GCC developers'
        self.add_package_author ('The GCC developers', canon_gcc)
        self.add_package_author ('The GCC Developers', canon_gcc)
or something similar do the trick?

2023-01-16  Jakub Jelinek  <jakub@redhat.com>

	PR other/108413
	* update-copyright.py (TestsuiteFilter): Add .mod and .rs extensions.
	(GCCCopyright): Add 'The fast_float authors' as external author.