$ cc -O2 -Wall -o uvd_sendmsg_nullfence uvd_sendmsg_nullfence.c
(clean, no diagnostics)
$ ls -l uvd_sendmsg_nullfence
-rwxr-xr-x  1 root  wheel  9120 Sep 20 20:51 uvd_sendmsg_nullfence
BUILD_OK_DF4501
(build host: DragonFly dfbsd 6.5-DEVELOPMENT x86_64, guest root@dfbsd, /tmp/df4501)