DF-5738/5739 build: verbatim production netbt sources -> KLD module
(captured from guest build run; full compiler invocation per .c in the
transcript below; final link line)

== copying verbatim production netbt sources ==
(for f in hci_event.c hci_link.c hci_misc.c hci_unit.c bt_input.c; cp /usr/src/sys/netbt/$f .)
setup.log records both sides' md5s:
  hci_event.c, hci_link.c, hci_misc.c, hci_unit.c, bt_input.c identical
== building KLD ==
cc -O2 ... -std=gnu11 -Werror -DKLD_MODULE ... -c harness.c
cc -O2 ... -c hci_stub.c
cc -O2 ... -c hci_event.c
cc -O2 ... -c hci_link.c
cc -O2 ... -c hci_misc.c
cc -O2 ... -c hci_unit.c
cc -O2 ... -c bt_input.c
cc -Wl,--build-id=sha1 -nostdlib -Wl,--hash-style=sysv -r -Wl,-d -o hci_link_harness.ko harness.o hci_stub.o hci_event.o hci_link.o hci_misc.o hci_unit.o bt_input.o
-rw-r--r-- 1 root root 44872 Oct 10 23:27 hci_link_harness.ko
== build OK ==

(rebuild after the fake-device fix: 48544 bytes, Oct 10 23:41;
 fix build against patched sources: 48664 bytes, Oct 11 00:22)