oox customshapepresetdata: empty is an empty string sequence
oox customshapepresetdata: empty is an empty string sequence

In case the data is empty, the data loader still set the proper type for
the sequence, while the generated code used a string sequence. Do the
same to keep testcases happy, there is no visual difference anyway.

Change-Id: I1b9be4486184a2a84c384f1365cc68dd45b8eee0

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