package: use SPDX short identifier for Boost Software License 1.0

We want to use SPDX identifier for license string as much as possible.
SPDX short identifier for Boost Software License 1.0 is BSL-1.0.

Signed-off-by: Rahul Bedarkar <rahulbedarkar89@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
5 files changed