4.12 Merge window part 1

As a user-space component, systemd-bootchart doesn't know anything before pid 1 comes up (it starts as pid 1, forks to run in the background, and execs the real init as pid 1). It also doesn't have access to kernel internals in detail.

If the majority of your boot cost is happening in user-space, systemd-bootchart is probably still the more useful tool (particularly for low-hanging fruit like "everything seems to be waiting for foo, can I avoid that?"), but if a large part of your boot cost is in kernel-space, this new thing is how you would analyze that part.