add script setup() and thread methods

src/wrk.lua

@@ -5,7 +5,8 @@ local wrk = {
    method  = "GET",
    path    = "/",
    headers = {},
-   body    = nil
+   body    = nil,
+   thread  = nil,
 }
 
 function wrk.resolve(host, service)
@@ -18,6 +19,13 @@ function wrk.resolve(host, service)
    wrk.addrs = addrs
 end
 
+function wrk.setup(thread)
+   thread.addr = wrk.addrs[1]
+   if type(setup) == "function" then
+      setup(thread)
+   end
+end
+
 function wrk.init(args)
    if not wrk.headers["Host"] then
       local host = wrk.host