[C++] Emscripten compiler fails building Arrow

The emscripten compiler (https://kripken.github.io/emscripten-site/) fails when compiling arrow with a few relatively minor issues:

• there is no -ggdb flag for debug support, only -g
• there is no execinfo.h, so even if Backtrace is found it cannot be used
• when using the emscripten compiler, even on mac, you cannot pass the -undefined dynamic_lookup argument