flowlib: fix match/actions assignment in null case

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
flowlib: print help for destroy table id/string

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
flow: in put_tables skip uid < 0

This allows applications to invalidate tables quickly
with a integer set by negating the uid value.

Also it was broken anyways.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
flowlib: fix bug in find_match

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
flowlib: fix pp_flow to use correct bit lengths

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>