Source for pthread-stubs

[R. G. Newbury]

I'm trying to do a full build of X following the instructions in the 
X.org Modular Builders Guide.
It get an error trying to build the xcb/libxcb directory, that I am 
missing  a library called "pthread-stubs xau"....I have pthread 
installed but yum cannot find anything called either pthread-stubs or 
xau...and I don't think that xau is actually a missing library, but what 
it is I have no idea. Yes, that is how it shows in the configure error 
output.
Does anyone know what/where/how I can find this library?