maint/utils/update-years.sh: replaced unportable 'sed -i' command.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>

maint/utils/update-years.sh

@@ -10,13 +10,13 @@ LINE="Copyright (C)"
 for i in $SOURCES; do
     # replace year: XXXX-YYYY -> XXXX-ZZZZ
     # add year: XXXX -> XXXX-ZZZZ
-    ${SED-sed} -i -e "
+    ${SED-sed} -e "
         1,20 {
                 /$LINE/s/-[0-9]\{4\}$/-$YEAR/
         };
         1,20 {
                 /$LINE/s/ [0-9]\{4\}$/&-$YEAR/
-    }" $i
+    }" $i > $i.tmp && mv -f $i.tmp $i
 done
 
 # special case