Warning on NODE_API_MODULE macro #888

The NODE_API_MODULE macro produces the missing-declarations warning:

... warning: no previous declaration for 'napi_value__* __napi_Init(napi_env, napi_value)' [-Wmissing-declarations]
napi_value _napi ## regfunc(napi_env env,
^
...: note: in expansion of macro 'NODE_API_MODULE'
NODE_API_MODULE(dnp3, Init);

Why __napi_XXX function in the macro is not static to suppress this warning?