[google/syzkaller] 24dc29: tools: add script for building of buildroot images

[Dmitry Vyukov]

Branch: refs/heads/master
Home: https://github.com/google/syzkaller
Commit: 24dc29dba51a8ae7ae86ebc04521a0b2223c531f
https://github.com/google/syzkaller/commit/24dc29dba51a8ae7ae86ebc04521a0b2223c531f
Author: Dmitry Vyukov <dvy...@google.com>
Date: 2021-10-18 (Mon, 18 Oct 2021)

Changed paths:
A tools/create-buildroot-image.sh

Log Message:
-----------
tools: add script for building of buildroot images

We used to use Debian-based images, but they have several issues:
1. They boot too slowly (we don't need full systemd power).
2. Systemd mounts cgroup controllers so that we can't use them during fuzzing
(can be mounted only once).
3. We have poor control over contents of the image.

This script creates lightweight buildroot-based images that boot fast.