Ryabitsev: Introducing b4 and patch attestation

Konstantin Ryabitsev introducesthe "b4" tool for kernel development. Developers and LWN readers willbe familiar with b4 under its previous name: get-lore-mbox. "On top of that, b4 alsointroduces support for cryptographic patch attestation, which makes itpossible to verify that patches (and their metadata) weren't modified intransit between developers. This is still an experimental feature, butinitial tests have been pretty encouraging." See this article for early coverage of theattestation feature.