haserl: add license file

Signed-off-by: Maxim Storchak <m.storchak@gmail.com>

utils/haserl/Makefile

@@ -16,6 +16,7 @@ PKG_SOURCE_URL:=@SF/haserl
 PKG_MD5SUM:=a9decddb508944d56f71dd2f821e2ec5
 PKG_MAINTAINER:=Maxim Storchak <m.storchak@gmail.com>
 PKG_LICENSE:=GPL-2.0
+PKG_LICENSE_FILES:=COPYING
 
 PKG_CONFIG_DEPENDS:= \
 	CONFIG_HASERL_with_lua \