Land rapid7#6998, Fix rapid7#6984 Undefined method 'winver' in ms10_092_schelevator

Author: wwebb-r7

modules/exploits/windows/local/ms10_092_schelevator.rb

@@ -85,7 +85,7 @@ def exploit
     end
 
     if check == Exploit::CheckCode::Safe
-      print_error("#{winver} is not vulnerable.")
+      print_error("#{sysinfo["OS"]} is not vulnerable.")
       return
     end