Land rapid7#2191, @todb-r7's fix to avoid race with powershell mixin

Author: jvazquez-r7

modules/exploits/windows/local/ms13_005_hwnd_broadcast.rb

@@ -8,6 +8,7 @@
 require 'msf/core'
 require 'rex'
 require 'msf/core/exploit/exe'
+require 'msf/core/exploit/powershell'
 
 class Metasploit3 < Msf::Exploit::Local
 	Rank = ExcellentRanking