package: bump copyrights to 2020

Run 'make update-copyright'.

tests/linear

@@ -3,6 +3,23 @@
 # Build a grammar whose LALR(1) parser has a given number of states.
 # Useful to test edge cases (e.g., 256 and 257 states, etc.).
 
+# Copyright (C) 2020 Free Software Foundation, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+# Written by Akim Demaille.
+
 class Linear
   def initialize(states)
     @states = states - 4