Build from source
Is there a recipe to build from source.
The description in README.md is not working.
`export EMSCRIPTEN=<emsdk_root>/fastcomp/emscripten` directory does not exist.
Running `./bin/build-emcpp.sh` failing with:
```
fatal error: 'openssl/conf.h' file not found
     #include <openssl/conf.h>
              ^~~~~~~~~~~~~~~~
```