If you are running bleeding-edge DragonFly, libpthread was broken for a short period. If you built anything in the last … 12 hours? You may want to rebuild it. If that doesn’t describe you, it’s a nonevent.
It’s funny that I’m reporting a short-term break in bleeding-edge operating system code as any sort of surprise. It shows something about how stable DragonFly-master is most of the time.
To be specific, if you rebuilt libc on an x86-64 system only, during the 12-hour or so period, you will need to rebuild it. You will need to rebuild statically linked threaded (only) programs as well.