bnc#885548: Adjust xlsx export of revisions to get it to work in Excel.

(cherry picked from commit fa44673e154ed4fb0b518b8850e2f6e4b9069531)

Conflicts:
	sc/source/filter/inc/XclExpChangeTrack.hxx
	sc/source/filter/xcl97/XclExpChangeTrack.cxx

Change-Id: I0058d9ddfea545390e615a3030171a366e333c85
Reviewed-on: https://gerrit.libreoffice.org/10394
Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>