Use symbolink for the "current" audit file

The current implementation of audit creates a file named audit.log and continues to write to that file until it is time to rotate the file. At that time it'll close the file and rename the file to: hostname-timestamp.log.

As part of the startup we need to determine the actual name of the file and rename the previous audit.log

Given that our supported platforms support links on the filesystem we can might as well write directly to the destination file and let audit.log point to the "current" file.