tdf#122892 sw: fix disappearing rows after table split
After fixing the infinite loop, the content of the merged table cell
with rowspan 3 is invisible, because its SwCellFrame and the SwRowFrame
containing it both have a height of 0.
This is due to funny code in SwTabFrame::Split(), which checks the bRet
flag before setting it to its final value, thus skipping the
lcl_AdjustRowSpanCells() call.
Change-Id: I96f9e9efdd5cae3a61da07995b8c31042fc59125
Reviewed-on: https://gerrit.libreoffice.org/68403
Tested-by: Jenkins
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>