Remove reference ot System.Security.Permissions

Author: roji

src/libraries/System.Transactions.Local/src/System/Transactions/Oletx/OletxTransaction.cs

@@ -5,7 +5,6 @@
 using System.Diagnostics;
 using System.Runtime.InteropServices;
 using System.Runtime.Serialization;
-using System.Security.Permissions;
 using System.Threading;
 using System.Transactions.DtcProxyShim;