cp#1000017 DOCX/RTF import: avoid fake tab char in footnotes

Word wants this, so it's added by the exporter to the document, but on
import we should ignore it.

Change-Id: Idcb669ba624bf462a50a85eb4aacf397afb6efe6
(cherry picked from commit b38629ae210b204a6d24d6e9c5c62eaaf563d494)