[PATCH 2.6] 1/2: Rename NAT helper structures

I forgot to Cc' the lists with this part of the patchset, here is the
forwarded message:

-- 
- Harald Welte [off-list ref]             http://www.netfilter.org/
============================================================================
  "Fragmentation is like classful addressing -- an interesting early
   architectural error that shows how much experimentation was going
   on while IP was being designed."                    -- Paul Vixie