Upgrade Linux to 4.7+
During the Tails 2.6 release process we had to do some hacks to keep building with Linux 4.6, in part due to boot from USB issues with Linux 4.7. That’s fine for Tails 2.6 and 2.7, but Linux 4.6 will go away from jessie-backports soonish, and our devel branch will stop building at some point, so we need to adjust our stuff to be able to build (and boot!) with 4.7+.
Feature Branch: feature/11818-linux-4.7