tiff: add licensing information

Signed-off-by: Jiri Slachta <slachta@cesnet.cz>

libs/tiff/Makefile

 
 PKG_NAME:=tiff
 PKG_VERSION:=4.0.3
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=http://download.osgeo.org/libtiff
 PKG_FIXUP:=autoreconf
 PKG_REMOVE_FILES:=autogen.sh aclocal.m4
 
+PKG_LICENSE:=BSD
+PKG_LICENSE_FILES:=COPYRIGHT
+
 PKG_INSTALL:=1
 
 PKG_CONFIG_DEPENDS:=CONFIG_PACKAGE_libtiffxx