Use new cmd_exec_get_pid

modules/exploits/windows/local/bypassuac_injection.rb

@@ -181,13 +181,13 @@ class Metasploit3 < Msf::Exploit::Local
     windir = expand_path("%WINDIR%").strip
     print_status("Spawning process with Windows Publisher Certificate, to inject into...")
     cmd = "#{windir}\\System32\\notepad.exe"
-    proc = client.sys.process.execute(cmd, nil, {'Hidden' => true })
+    pid = cmd_exec_get_pid(cmd)
 
-    if proc.nil? or proc.pid.nil?
+    unless pid
       fail_with(Exploit::Failure::Unknown, "Spawning Process failed...")
     end
 
-    proc.pid
+    pid
   end