For what it's worth, I found that the autoconfig rules used in the Python sources (which may not really relate to the issue here) did not cause the threads library to be added to the linking rules. This was partly because it expected to find "cthreads.h" in the "mach" directory.
In addition, the autoconf source needed a line similar to: LIBS="$LIBS -lthread" under the "CTHREAD" set of rules. It may be that configuration code that sees a "MACH" definition may believe that the threading libraries are part of the main system libraries, and not an external library that needs to be linked in. Unfortunately, my Mach history is not sufficient to comment further. Thanks, -Brent
