I was able to build tor using the PNaCl toolchain by removing
-z relro -z now from the make file and compiling with
make CC=<pnacl clang binary>. Everything run by
make test passes, and the resulting binary seems to function as normal. I was a bit surprised at how easy it was.
Is this a sensible thing to do? It seems like it would reduce the risk from any remote execution vulnerability tor might have.