Conditional logging of rule file name and line number.

[marcstern]

Each time a rule triggers and is logged, it generates a line in the audit log (and possibly in the error log) containing the name of the file containing the rule, as well as the line number.
Although it may be useful in some cases, this also wastes a lot of disk space ("wastes" because we can easily find the rule thanks to its id).
Furthermore, when using nested macros (with httpd mod_macro), the filename may be several thousands characters long (real life experience); this becomes totally insane.
We should have a directive (or a compile flag) to disable that logging.
Ex. of compile flag: #marcstern@9e68805