windows memory card fixes/cleanup

stepmania/src/arch/MemoryCard/MemoryCardDriver.h

@@ -4,7 +4,9 @@
 
 struct UsbStorageDevice
 {
-	UsbStorageDevice()
+	UsbStorageDevice() { MakeBlank(); }
+
+	void MakeBlank()
 	{
 		iBus = -1;
 		iDeviceOnBus = -1;
@@ -18,11 +20,18 @@ struct UsbStorageDevice
 	int iUsbStorageIndex;
 	CString	sOsMountDir;	// WITHOUT trailing slash
 
+	bool IsBlank() { return sOsMountDir.empty(); }
+
 	bool operator==(const UsbStorageDevice& other)
 	{
-		return 
-			iBus==other.iBus &&
-		  iDeviceOnBus==other.iDeviceOnBus;  // every time a device is plugged in, it gets a unique device number
+		// ugly...
+#if _WINDOWS
+		// we don't have hub/port number info on Windows
+		return sOsMountDir==other.sOsMountDir;  // every time a device is plugged in, it gets a unique device number
+#else	// LINUX or other
+		return iBus==other.iBus &&
+			iDeviceOnBus==other.iDeviceOnBus;  // every time a device is plugged in, it gets a unique device number
+#endif
 	}
 };