Bug 143173 No error for recursive including when exporting a report to a library
Steps to reproduce: 1.New a library named "Lib", add a lable in it 2.New a report, extends Lib.label 3.Export the report, choose target library "Lib" Expected result: Error to warn the recursive including Actual result: The target library includes itself without error
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/util/ElementExportUtil.java
*            file name of the target library
	 * @param canOverride
	 *            indicates whether the element with the same name in target
	 *            library will be overriden.
	 * 
	 * @throws DesignFileException
	 *             if error encountered when open library file with the given
	 *             file name.
	 * @throws SemanticException
	 *             if error encountered when element name is duplicate in the
	 *             target library.
	 * @throws IOException
	 *             if error encountered when writing file.
	 * @throws IllegalArgumentException
	 *             if the element to export is not in design file.
	 */
	public static void exportElements( List elementsToExport,
			String libraryFileName, boolean canOverride )
			throws DesignFileException, SemanticException, IOException
	{
		DesignSession session = null;
		
		Iterator iter = elementsToExport.iterator( );
		while ( iter.hasNext( ) )
		{
			DesignElementHandle elementToExport = (DesignElementHandle) iter
					.next( );
			ElementExporter.checkElementToExport( elementToExport );
			if ( session == null )
				session = elementToExport.getModule( ).getSession( );