SwIoSystem::GetFileFilter: prevent out of bounds string access
SwIoSystem::GetFileFilter: prevent out of bounds string access

Change-Id: I0f2ebc9cbad16534b50083cc6d13ee042c2ff869

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