fix SwIndexReg::~SwIndexReg assert in fdo68332-2.docx
fix SwIndexReg::~SwIndexReg assert in fdo68332-2.docx

SwParaSelection sets a mark on the cursor, but there is no need to do that.
DelFullPara will delete the SwTxtNode anyway.

Change-Id: I99b8dd637bd4d2b49a555e147514a2def19fa0bf
Reviewed-on: https://gerrit.libreoffice.org/14054
Reviewed-by: Michael Stahl <eef8671db506f9731c0438a7613853b6391ca841@redhat.com>
Tested-by: Michael Stahl <eef8671db506f9731c0438a7613853b6391ca841@redhat.com>

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