[Pkg-ulog-acctd-general] Flush enhancements

[Amin Azez]

I intend to modify ulog-acctd to respond to a new signal by performing a
flush and resetting the flush counter.

This will allow flushing to be synchronized with or controlled by an
external (parent?) process.

ulod-acctd will also reopen the log file after the flush; thus the
parent process will typically first rename the logfile (while it is
still held open by ulog-acctd) and then send the signal.

When a new logfile appears, ulog-acctd must have finished the flush.

Any opinions?

Sam