use the new check also in exploit()

Author: jvazquez-r7

modules/exploits/windows/local/ms14_009_ie_dfsvc.rb

@@ -147,7 +147,7 @@ def exploit
 
     mscorlib_version = get_mscorlib_version
 
-    unless mscorlib_version < NET_VERSIONS[net_version]["mscorlib"]
+    unless valid_mscorlib_version?(net_version, mscorlib_version)
       fail_with(Failure::NotVulnerable, ".NET Installation not vulnerable")
     end