OpenEventLog() takes two string pointers

Hello,

[MSDN specifications](http://msdn.microsoft.com/en-us/library/windows/desktop/aa363672\(v=vs.85\).aspx) defines OpenEventLog() arguments as strings:

```C
HANDLE OpenEventLog(
  _In_  LPCTSTR lpUNCServerName,
  _In_  LPCTSTR lpSourceName
);
```