elb links without -rdynamic so dlsym(RTLD_DEFAULT, "handle_request")
returns NULL at runtime. http_set_handler stores the name as active but
never finds a function pointer, causing every request to return
"el-runtime: no http handler registered" even after http_serve is called.
Fix: add a __attribute__((constructor)) in web_stubs.c that calls
el_runtime_register_handler("handle_request", handle_request) directly,
bypassing dlsym entirely. The handler is in the registry before main()
runs, so http_lookup_active() finds it on the first request.
will.anderson