Use SPDX 3.0 license identifier

SPDX released version 3 of their license list
(https://spdx.org/licenses/),
which changed the FSF licenses to explicitly end in -only or -or-later
instead of relying on an easy to miss + symbol.

Bug: T183858
Change-Id: Id485b3c24cf31d242a6ad5e451cc086d400c8521