o Axe non-pcpu flowtable implementation. It wasn't enabled or used,
  and probably is a leftover from first prototyping by Kip. The
  non-pcpu implementation used mutexes, so it doubtfully worked
  better than simple routing lookup.
o Use UMA_ZONE_PCPU zone for pointers instead of [MAXCPU] arrays,
  use zpcpu_get() to access data in there.
o Substitute own single list implementation with SLIST(). This
  has two functional side effects:
  - new flows go into head of a list, before they went to tail.
  - a bug when incorrect flow was deleted in flow cleaner is
    fixed.
o Due to cache line alignment, there is no reason to keep
  different zones for IPv4 and IPv6 flows. Both consume one
  cache line, real size of allocation is equal.
o Rely on that f_hash, f_rt, f_lle are stable during fle
  lifetime, remove useless volatile quilifiers.
o More INET/INET6 splitting.

Reviewed by:	adrian
Sponsored by:	Netflix
Sponsored by:	Nginx, Inc.
libutil/pw_util.3: Fix two prototypes.

Reported by:	marino
Obtained from:	DragonFlyBSD (e82b5d3dfa969bfcda5ffadceccc682b6bdcd077)
MFC After:	3 days
Remove unused FL_NOAUTO.