Fix memory leak (Coverity defect #2089).

Fix memory leak (Coverity defect #2089).
Ignore script if subtable is missing (Coverity defect #2088).
Fix possible null pointer dereference (Coverity defect #784) and memory
    leak (Coverity defects #785, #786).
Don't copy FcCharSet if we're going to throw it away anyway. (Reported by
    Kenichi Handa).
reviewed by: plam