Due to sw_redlinehide the SwTextNode::MakeFrame() is skipped on
SwTextNodes that are merged due to redlining. But then the
IgnoreStart/IgnoreEnd flags on the hints are not initialised and some
assert like assert(pHt->IsFormatIgnoreStart()) fails.

tdf90056-1.odt is an example document.

There doesn't appear to be a convenient place to initialise it per-node
as it is finished; the ODF import inserts APPEND_PARAGRAPH before
inserting the hints themselves.

So remove the initialisation from MakeFrame() and just do it in
SwReader::Read().

Change-Id: Ib33fe3033fc05bd2f5ef2ac8d059d587642ccf48
Reviewed-on: https://gerrit.libreoffice.org/68748
Tested-by: Jenkins
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>