First step in removing welding between ipfw(4) and dummynet.
o Do not use ipfw_insn_pipe->pipe_ptr in locate_flowset(). The
_ipfw_insn_pipe isn't touched by this commit to preserve ABI compatibility.
o To optimize the lookup of the pipe/flowset in locate_flowset()
introduce hashes for pipes and queues: - To preserve ABI compatibility utilize the place of global list pointer for SLIST_ENTRY. - Introduce locate_flowset(queue nr) and locate_pipe(pipe nr).
o Rework all the dummynet code to deal with the hashes, not global
lists. Also did some style(9) changes in the code blocks that were touched by this sweep: - Be conservative about flowset and pipe variable names on stack, use "fs" and "pipe" everywhere. - Cleanup whitespaces. - Sort variables. - Give variables more meaningful names. - Uppercase and dots in comments. - ENOMEM when malloc(9) failed.