o In pf_normalize_ip() we don't need mtag in
  !(PFRULE_FRAGCROP|PFRULE_FRAGDROP) case.
o In the (PFRULE_FRAGCROP|PFRULE_FRAGDROP) case we should allocate mtag
  if we don't find any.

Tested by:	Ian FREISLICH <ianf cloudseed.co.za>
Provide compatibility #define after r265408.

Suggested by:	truckman