[REVIEW] RTF import: an empty table grid can't have implicit merges

[Miklos Vajna]

Hi Cedric,

See
http://cgit.freedesktop.org/libreoffice/core/commit/?id=75378a82e1a9e921cebe221427baca24cad47baf

It fixes a crash when implicit mergeded cells and nested tables are
involved.

Could you sign-off and push to -3-5, please?

Thanks,

Miklos