# guest compiler output (final successful builds; -O2, cc 8.3 DragonFly)
$ cc -O2 -o /tmp/df3157 /tmp/df3157.c
$ cc -O2 -o /tmp/fhtest /tmp/fhtest.c
/tmp/fhtest.c: In function 'main':
/tmp/fhtest.c:49:3: warning: implicit declaration of function 'close'; did you mean 'pclose'? [-Wimplicit-function-declaration]
   49 | close(fd);
      | pclose
$ cc -O2 -pthread -o /tmp/hammer /tmp/hammer.c
$ cc -O2 -pthread -o /tmp/chain /tmp/chain.c
# patched kernel builds:
$ cd /usr/src && make -j 6 nativekernel   -> KBUILD-OK (x2, /tmp/kbuild.log /tmp/kb3.log)
$ make installkernel                      -> INST-OK