For broker.log and cluster.log: there was a race condition. A worker's
first IOSource that it processes is potentially Broker if there were
no packets available yet and thread scheduling happens to work out
such that network connections (inside CAF threads) become established
before we enter the main I/O loop. Such peering establishments would
generate logs with timestamp 0 as there was not yet any code path
taken that would update network_time.
For reporter.log: any non-worker (packet-processing) node would just
unnecessarily use a timestamp of 0 for their reporter messages.
This also installs symlinks from "zeek" and "bro-config" to a wrapper
script that prints a deprecation warning.
The btests pass, but this is still WIP. broctl renaming is still
missing.
#239
