This commit in the 4.2 branch is similar to the one in master
(9f2e53ef).

The postal address of the FSF has changed. Instead of updating it,
use the recommendation from
  https://www.gnu.org/licenses/gpl-howto.en.html
for the copyright notice, i.e. no longer use the postal address;
just give the web page <https://www.gnu.org/licenses/>.

This commit updates the copyright notice of almost all files (the
remaining files will be updated later). It has been obtained with

  perl -p0i -e 'BEGIN { $s =
      "If not, see\nhttps://www.gnu.org/licenses/ or write".
      " to the Free Software Foundation, Inc.,\n51 Franklin St,".
      " Fifth Floor, Boston, MA 02110-1301, USA." }
      s# +\Q$s\E#\nIf not, see <https://www.gnu.org/licenses/>.#g' \
    $(git ls-files)