ipfilter bug #558 add in some missing frag table function comments.

Approved by:	glebius (mentor)
Obtained from:	ipfilter CVS repo (r1.36)


git-svn-id: svn+ssh://svn.freebsd.org/base/head@272052 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f