Fix calculation of internal leading
Fix calculation of internal leading

Stupid me, I totally messed this up! God only knows how many non-bugs
people had to fix because of this typo.

Has the side effect of fixing fdo#64972 (among many others of course,
but this is the only one still open).

Change-Id: I9d8fdb6d37d4af9b0ac973902e469e0bd3a2408a

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