fix leaks in SwGlossaryHdl::NewGlossary and SwGlossaryHdl::DelGlossary
and SwGlossaryHdl::InsertGlossary error paths

Change-Id: Iaf98fea08cd44bf68885e053854cf65372fcfc2c
Reviewed-on: https://gerrit.libreoffice.org/60495
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>