Fix crash in WMF import - fdo#36991.
Fix crash in WMF import - fdo#36991.

(cherry picked from commit c4361c93de2b9661d59bc4aa799dffea7ad579e2)

Signed-off-by: Tor Lillqvist <d7e1c1a966af497a2abd6e0cf00cbb63dd0496e4@novell.com>

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