OEMReadDebugByte in CE6.0

I quite often run a simple serial terminal using the debug port, having this we can control the platform without active sync, a keybaord or even an LCD, but when running from CE6.0 the application doesn't build because OEMReadDebugByte fails. If you want an app to be able to do the equivalent of OEMReadDebugByte instead use the function InputDebugCharW.