Integrate tools/regression/file/closefrom into the build

Do not integrate into Kyua (see https://github.com/jmmv/kyua/issues/90
for more details)
Integrate file/{dup,fcntlflags,flock} into the build/kyua

tests/sys/flock/flock.sh (the test driver for flock_helper.c)
was obtained from EMC / Isilon Storage Division

Sponsored-by: EMC / Isilon Storage Division
Add a reminder for integrating this in to pjdfstest
Remove hand-rolled compile recipe

Sponsored-by: EMC / Isilon Storage Division