vlog: Make vlog_should_drop() thread-safe.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ed Maste <emaste@freebsd.org>
vlog: Remove unused function vlog_get_log_file().

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ed Maste <emaste@freebsd.org>
vlog: Remove unused function vlog_exit().

This is harder to implement once threads are introduced.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ed Maste <emaste@freebsd.org>
system-stats: Remove worker process support.

The worker process implementation isn't thread-safe and, once OVS
itself is threaded, it doesn't make much sense to have a worker
process anyway.

Signed-off-by: Ben Pfaff <blp@nicira.com>
worker: Delete library.

It had no remaining users.

Signed-off-by: Ben Pfaff <blp@nicira.com>