By implementing btlr support in
SwTextFrame::SwitchVerticalToHorizontal(SwRect), so not only
invalidation but paint rectangle is also correct, which means actual
text painting happens.

Change-Id: I4215799ff63c93b300e4e8f97c6824f75d7c5401
Reviewed-on: https://gerrit.libreoffice.org/70797
Tested-by: Jenkins
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>