buildroot

modem-manager: add COPYING.LIB to LICENSE_FILES

ModemManager and mmcli are GPLv2+ (COPYING file applies) and
libmm-glib is LGPLv2.1+ (COPYING.LIB file applies).

Also, setup hashes of the license files, for a correct
"make legal-info".

Signed-off-by: Aleksander Morgado <aleksander@aleksander.es>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>