Multiqueue BPF support and other BPF features

by Takuya ASADA for FreeBSD

The project goal is to support multiqueue network interface on BPF, and provide interfaces for multithreaded packet processing using BPF. BPF is raw interface of network devices, which allows to receive / send Data Link Layer frame directly. Modern high performance NICs have multiple receive/send queues and RSS feature, this allows to process packet concurrently on multiple processors. Main purpose of the project is to support these hardware and get benefit of parallelism.