The DISABLE_DYNLOADING case in ImpFilterLibCacheEntry::GetImportFunction()
had apparently been broken from the start, but nobody never noticed as
the common formats (PNG, JPEG, GIF etc) use a more "internal"code
path. The problem was noticed now with a TIFF image in a presentation.

The fix for the import case seems to work, but I could not test the
fix for the export case.

Change-Id: Icbd33c7cb654136a562f18b06d5b0896e701bf3d