add script setup() and thread methods

scripts/addr.lua

@@ -0,0 +1,22 @@
+-- example script that demonstrates use of setup() to pass
+-- a random server address to each thread
+
+local addrs = nil
+
+function setup(thread)
+   if not addrs then
+      addrs = wrk.lookup(wrk.host, wrk.port or "http")
+      for i = #addrs, 1, -1 do
+         if not wrk.connect(addrs[i]) then
+            table.remove(addrs, i)
+         end
+      end
+   end
+
+   thread.addr = addrs[math.random(#addrs)]
+end
+
+function init(args)
+   local msg = "thread addr: %s"
+   print(msg:format(wrk.thread.addr))
+end