Incidentally, on the latest releases of Darwin, the default compiler (with is llvm-based) aborts when compiling mapping.c. I still use regular gcc, so haven't attempted to report the bug.
I've seen that too. It's normally sufficient to manually compile mapping.c with gcc and re-run make (with the default llvm-gcc) after that. We never got around to report that to Apple since there seemed to be tickets on that issue already, though that's a lame excuse if the errors in reality are separate.
It would be nice to support clang natively as well but I guess that will be a major exercise in autoconf/makefile hacking.