SwRTFWriter::WriteStream: fix leak
SwRTFWriter::WriteStream: fix leak

Change-Id: I86205aeeefd727090b780bc41a959200affa9920

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core