[REVIEW 3-6] fdo#54862 .doc merged cells import regression fix

[Caolán McNamara]

As https://bugs.freedesktop.org/show_bug.cgi?id=54862
fix
http://cgit.freedesktop.org/libreoffice/core/commit/?id=b966a09c2da9441961c93c44be556399575db849

commit 567c1db25bd705faac44203e4a3d01d0f5e1385c reverted a pile of other
commits, including 858b5b4f36a357fe7192e7c2ed9cc3cdfc81fd8f but didn't
revert the ++n of that commit, leading to merge groups getting skipped.
Quite likely a bunch of .doc table complaints lead back to this.

C.