=== PATCHED-module fix validation run (guest up, post-fix) ===
$ kldload netgraph.ko; kldload /usr/obj/usr/src/sys/netgraph/socket/ng_socket.ko   # patched
$ cc -O -o /root/df3516 /root/df3516.c
$ /root/df3516
[*] sendto(NGM_SHUTDOWN) = 52 errno=0 (Undefined error: 0)
[*] connect() (should panic the kernel)
[!] connect returned -1 errno=57 (Socket is not connected) - no panic?
EXIT=0
GUEST_STILL_ALIVE

=== patched module build (tail) ===
cc ... -c /usr/src/sys/netgraph/socket/ng_socket.c   [with fix.diff applied]
cc -Wl,--build-id=sha1 ... -r -Wl,-d -o ng_socket.ko ng_socket.o