Commit f5938e8ff3 started dropping all
messages before we become a monitor, but the last one was getting
through.
This drops also the last NameLost message, which indicatse the switch
from a regular peer to a monitor.
A connection becomes a monitor the moment it loses its unique name, so any
messages received before that should not be dumped to the console.
Currently, we print NameAcquired and NameLost for the unique name of the
peer that becomes the monitor, simply discard all messages until we
receive our NameLost signal.
busctl is not part of libsystemd, and should not be stored under libsystemd.
In particular this is confusing because busctl is linked with libshared, but
stuff in libsystemd is not supposed to depend on libshared.
