store /sys/block name in Linux

stepmania/src/arch/MemoryCard/MemoryCardDriver.h

@@ -28,6 +28,7 @@ struct UsbStorageDevice
 	CString sSerial;
 	CString sDevice;
 	CString	sOsMountDir;	// WITHOUT trailing slash
+	CString sSysPath;   // Linux: /sys/block name
 	enum State
 	{
 		/* Empty device.  This is used only by MemoryCardManager. */

stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_Linux.cpp

@@ -278,6 +278,7 @@ void GetNewStorageDevices( vector<UsbStorageDevice>& vDevicesOut )
 			UsbStorageDevice usbd;
 
 			CString sPath = sBlockDevicePath + sDevice + "/";
+			usbd.sSysPath = sPath;
 
 			/* Ignore non-removable devices. */
 			CString sBuf;