reaahead-collector abuses the audit logging facility to discover which files
are accessed at boot time to make a pre-load list

Add a tuning option to audit_backlog_wait_time so that if auditd can't keep up,
or gets blocked, the callers won't be blocked.

Bump audit_status API version to "2".
Signed-off-by: NRichard Guy Briggs <rgb@redhat.com>
Signed-off-by: NEric Paris <eparis@redhat.com>