I'm seeing this weird cmake error when trying to build plfs on an centos system:

/usr/bin/gcc     -DCHECK_FUNCTION_EXISTS=pthread_create  -fPIC CMakeFiles/cmTryCompileExec.dir/CheckFunctionExists.c.o  -o cmTryCompileExec -rdynamic -lpthreads 
/usr/bin/ld: cannot find -lpthreads

Which seems like a straightforward problem with finding libpthreads.  But I've created a sample pthreads program and it builds and runs correctly:

> /usr/bin/gcc -c -o p_hello.o p_hello.c
> /usr/bin/gcc -o p_hello -fPIC -rdynamic -lpthread p_hello.o
> ./p_hello 5
Hello from thread 0
Hello from thread 1
Hello from thread 2

Anyone see anything obvious that I'm missing?