fdo#79384: replace the work-around with a different one

Word will reject Shift-JIS following \loch, but apparently OOo could read
and (worse) write such documents, so accept Shift-JIS regardless of run
charset type.

(cherry picked from commit d71387ca81b61416b9a7b82cd6cf67d496b81fc2)

Conflicts:
	writerfilter/source/rtftok/rtfdocumentimpl.cxx

Change-Id: Ib181956e9f218548a52037dd76fa1d3ecdc006bd
Reviewed-on: https://gerrit.libreoffice.org/9633
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Miklos Vajna <vmiklos@collabora.co.uk>