licensing: Add licensing metadata to many packages

licensing: Add licensing metadata to many packages
Two new variables are introduces to many packages, namely PKG_LICENSE and
PKG_LICENSE_FILES - there may be more than one license applied to packages,
and these are listed in the PKG_LICENSE variable and separated by spaces.
All relevant license files are also added to the PKG_LICENSE_FILES variable,
also space separated.

The licensing metadata is put into the bin/<platform>/packages/Packages file
for later parsing. A script for that is on it's way!

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@33861 3c298f89-4303-0410-b956-a3cf2f4a3e73