DOCX styles: Don't export <w:next> for styles that point to themselves.
DOCX styles: Don't export <w:next> for styles that point to themselves.

Change-Id: I3f877f9dc836686e91df70ff1e02e67ca25b4a84

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