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/util/ModelUtil.java
* Filtrates the table layout tasks.
	 * 
	 * @param tasks
	 *            the table layout tasks
	 * @return a list contained filtrated table layout tasks
	 */
	public static List filterLayoutTasks( List tasks )
	{
		List retList = new ArrayList( );
		Set elements = new LinkedHashSet( );
		for ( int i = 0; i < tasks.size( ); i++ )
		{
			RecordTask task = (RecordTask) tasks.get( i );
			if ( task instanceof LayoutRecordTask )
			{
				DesignElement compoundElement = (DesignElement) ( (LayoutRecordTask) task )
						.getTarget( );
				if ( !elements.contains( compoundElement ) )
				{
					retList.add( task );
					elements.add( compoundElement );
				}
			}
		}
		return retList;
	}
	/**
	 * Returns the first fatal exception from the given exception list. The
	 * fatal exception means the error should be forwarded to the outer-most
	 * host module and stops opening module.