How to make Fedora4 build threadsafe?

I experienced this error while running this ./configure:

./configure --enable-thread-safety --prefix=/cgrid/local/postgresql

on FedoraCore4:

checking thread safety of required library functions... no
configure: error:
*** Thread test program failed.  Your platform is not thread-safe.
*** Check the file 'config.log'for the exact reason.
***
*** You can use the configure option --enable-thread-safety-force
*** to force threads to be enabled.  However, you must then run
*** the program in src/tools/thread and add locking function calls
*** to your applications to guarantee thread safety.

[mengland@localhost postgresql-8.1.3]$


Is there anything I can do to fix this?  Install some extra/different
libraries?  (I'm trying a ./configure run after installing
"linuxthreads-devel" right now.)

I didn't have this problem building 8.1.0/8.1.1 with the same procedure on
Centos4.1 and Debian3.1 (sarge) systems, for whatever that's worth.

-Matt