tools/patch-image: add PKG_RELEASE

There is no versioning information in the patch-image code nor the
Makefile. Consider it as first release by adding PKG_RELEASE.

Motivation is the tracking of changes in the buildsystem, which requires
versioning of packages.

Also update copyright.

Signed-off-by: Paul Spooren <mail@aparcar.org>

tools/patch-image/Makefile

@@ -1,5 +1,5 @@
 # 
-# Copyright (C) 2007-2012 OpenWrt.org
+# Copyright (C) 2007-2020 OpenWrt.org
 #
 # This is free software, licensed under the GNU General Public License v2.
 # See /LICENSE for more information.
@@ -7,6 +7,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=patch-image
+PKG_RELEASE:=1
 
 include $(INCLUDE_DIR)/host-build.mk