Fixes crash on two-character VML path commands.

Change-Id: Ia1abca37352b1feb20a41b4bac68ecb9e40ed8dc
Reviewed-on: https://gerrit.libreoffice.org/3093Tested-by: Miklos Vajna <vmiklos@suse.cz>
Reviewed-by: Eilidh McAdam <eilidh.mcadam@gmail.com>
Reviewed-by: Miklos Vajna <vmiklos@suse.cz>