Early daemons like dhcpleased(8), slaacd(8), unwind(8), resolvd(8)

Early daemons like dhcpleased(8), slaacd(8), unwind(8), resolvd(8)
are started before syslogd(8).  This resulted in ugly sendsyslog(2)
dropped logs and the real message was lost.
Create a temporary stash for log messages within the kernel.  It
has a limited size of 100 messages, and each message is truncated
to 8192 bytes.  When the stash is exhausted, the well-known dropped
message is generated with a counter.  After syslogd(8) has setup
everything, it sends a debug line through libc to flush the kernel
stash.  Then syslogd receives all messages from the kernel before
the usual logs.
OK deraadt@ visa@