Does anyone know where I can find sources for a POSIX pthread library?

I'm trying to build quake2-0.2.1. The configure script apparently doesn't
like pth, which is the only choice in pkgsrc. Google has led me pretty much
nowhere.

From running configure:

checking for the pthreads library -lpthreads... no
checking whether pthreads work without any flags... no
checking whether pthreads work with -Kthread... no
checking whether pthreads work with -kthread... no
checking for the pthreads library -llthread... no
checking whether pthreads work with -pthread... no
checking whether pthreads work with -pthreads... no
checking whether pthreads work with -mthreads... no
checking for the pthreads library -lpthread... no
checking whether pthreads work with --thread-safe... no
checking whether pthreads work with -mt... no
configure: error: "POSIX threads required!"


-- 
Rick Kelly  rmk@rmkhome.com  www.rmkhome.com