src: make process.dlopen() load well-known symbol
Look for symbol node_register_module_v${NODE_MODULE_VERSION}
if the
add-on didn't self-register. This can be used to create add-ons that
support multiple Node.js versions from a single shared object.
An experiment to make add-on loading more flexible. Can be extended to n-api, cc @nodejs/n-api.
Longer term, I'd like to get rid of the __attribute__((constructor))
approach. It's convoluted and complicated for no good reason.