Release inviscursor in IrrDeviceLinux. Thanks @hendu for reporting.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@4306 dfc29bdd-3216-0410-991c-e03cc46cb475

source/Irrlicht/CIrrDeviceLinux.cpp

@@ -2160,6 +2160,7 @@ CIrrDeviceLinux::CCursorControl::~CCursorControl()
 #ifdef _IRR_COMPILE_WITH_X11_
 void CIrrDeviceLinux::CCursorControl::clearCursors()
 {
+	XFreeCursor(Device->display, invisCursor);
 	for ( u32 i=0; i < Cursors.size(); ++i )
 	{
 		for ( u32 f=0; f < Cursors[i].Frames.size(); ++f )