Fix memory leak
Fix memory leak

The same was done in mork driver [1] and mork driver was derived from
mozab driver.

[1] 317306710d8f7c16bd6b9edc1e0af7e0e757cbac

Change-Id: I64bc85819810707511a3cebd43802066cd94a727

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