This will avoid breaking the build whenever a non-major kernel update
happens. In the update script, we map each kernel version to the latest
patch for the latest kernel version less than or equal to what we
have packaged.
This is an updated version of the former upstream,
https://github.com/AndroidHardeningArchive/linux-hardened, and provides
a minimal set of additional hardening patches on top of upstream.
The patch already incorporates many of our hardened profile defaults,
and releases are timely (Linux 5.5.15 and 5.6.2 were released on
2020-04-02; linux-hardened patches for them came out on 2020-04-03 and
2020-04-04 respectively).
