Perhaps linkage error when exposing C++ library on Linux

[shawnLeeZX]

I figure that I may not be able to solve the issue in short term, and the author is busy on development lines, so it may be better to note the bug down.

I tried to run the hello world example: https://github.com/clasp-developers/demo-clasp-cxx-interoperation, on Linux (Ubuntu 16.04 and Arch Linux), and got the following error:

 Starting Boehm cclasp 0.4.2-60-gcefe61b ... loading image... it takes a few seconds 
../../src/gctools/interrupt.cc:302 Hit a fatal error in llvm: Program used external function '_ZTH9my_thread' which could not be resolved!

I can run the clasp interpreter without any issue. I may need to learn how clasp and clang handles their symbol tables to figure out why.

I believe all Linux users are blocked by this bug, thus it is quite critical. Hope it would be fixed soon.