ruby 2.2 compatibility

https://bugs.ruby-lang.org/issues/10314

Author: dmooray

lib/msf/core/exploit/sunrpc.rb

@@ -84,7 +84,7 @@ def sunrpc_create(protocol, program, version, time_out = timeout)
     rpcobj.pport = arr[5]
   end
 
-  def sunrpc_call(proc, buf, timeout = timeout)
+  def sunrpc_call(proc, buf, timeout = timeout())
     ret = rpcobj.call(proc, buf, timeout)
     raise ::Rex::Proto::SunRPC::RPCError, "#{rhost}:#{rport} - SunRPC - No response to SunRPC call for procedure: #{proc}" unless ret