health checker does not support stream directive

[vesafb]

The health checker can't be used in the stream directive.

The snippet of nginx.conf:

stream {
    lua_shared_dict healthcheck 1m;
    init_worker_by_lua_block {
        local hc = require "resty.upstream.healthcheck"

The error message is: nginx: [emerg] "lua_shared_dict" directive is not allowed here in ./conf/nginx.conf:121