pf: address family must be set when creating a pf_fragment
Fix a panic when handling fragmented ip4 packets with 'drop-ovl' set.
In that scenario we take a different branch in pf_normalize_ip(), taking us to
pf_fragcache() (rather than pf_reassemble()). In pf_fragcache() we create a
pf_fragment, but do not set the address family. This leads to a panic when we
try to insert that into pf_frag_tree because pf_addr_cmp(), which is used to
compare the pf_fragments doesn't know what to do if the address family is not
set.
Simply ensure that the address family is set correctly (always AF_INET in this
path).
When we try to look up a pf_fragment with pf_find_fragment() we compare (see
pf_frag_compare()) addresses (and family), but also protocol. We failed to
save the protocol to the pf_fragment in pf_fragcache(), resulting in failing
reassembly.
PR: 200330