core/pkg-util: pass package directory and name when saving license files

core/pkg-util: pass package directory and name when saving license files

This will be useful when checking the hashes of the license files.

[Peter: use '.' as buildroot directory so /buildroot.hash isn't checked]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Luca Ceresoli <luca@lucaceresoli.net>
Cc: Peter Korsgaard <peter@korsgaard.com>
Cc: Rahul Bedarkar <rahulbedarkar89@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>