Use of thread-local storage causes a crash

[murarth]

rusti=> thread_local!(static FOO: int = 1);

crashes with:

Relocation type not implemented yet!
UNREACHABLE executed at /home/rustbuild/src/rust-buildbot/slave/nightly-linux/build/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp:266!
Aborted (core dumped)