Add Destructor to SerialPort class (#102)

***NO_CI***

Author: networkfusion

System.IO.Ports/SerialPort.cs

@@ -771,6 +771,14 @@ internal static SerialPort FindDevice(int index)
             return null;
         }
 
+        /// <summary>
+        /// Destructor.
+        /// </summary>
+        ~SerialPort()
+        {
+            Dispose(false);
+        }
+
         /// <summary>
         /// Releases the unmanaged resources used by the <see cref="SerialPort"/> and optionally
         /// releases the managed resources.