[bug#30464] shepherd logging

[Danny Milosavljevic]

>   https://git.savannah.gnu.org/cgit/hurd/hurd.git/tree/startup/startup.c#n731
> 
> It’s comparable to /dev/kmsg, but it exists before file system servers
> are brought up, which is why it doesn’t have an entry in the file
> system hierarchy.

Huh, so it's just connected to stderr?  That means it should work fine already
with no changes in shepherd.  Nice!

Just to be sure, it is possible to read out these messages and log them to a
file later on, right?