Do minor c code cleanup

modules/exploits/linux/local/desktop_privilege_escalation.rb

@@ -174,10 +174,12 @@ struct pam_message {
   int msg_style;
   const char *msg;
  };
+
 struct pam_response {
   char *resp;
   int resp_retcode;
 };
+
 struct pam_conv {
   int (*conv)(int num_msg, const struct pam_message **msg,
   struct pam_response **resp, void *appdata_ptr);