tdf#108524 sw: try to split rows that contain 1-col sections

We used to not even attempt to split a row that contains sections. Relax
this condition and try to split the row in case the table itself is not
in a section (to avoid recursion) and the section has no columns.

This is needed, but not enough to split the section in the bugdoc.

Change-Id: I6ad0d6eb18611f108ae29e4feea7101ffe552c48
Reviewed-on: https://gerrit.libreoffice.org/38824Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>

sw/source/core/layout/tabfrm.cxx

@@ -915,7 +915,22 @@ static bool lcl_FindSectionsInRow( const SwRowFrame& rRow )
             else
             {
                 // #i26945# - search only for sections
-                bRet = pTmpFrame->IsSctFrame();
+                if (pTmpFrame->IsSctFrame())
+                {
+                    bRet = true;
+
+                    if (!rRow.IsInSct())
+                    {
+                        // This row is not in a section.
+                        if (const SwFrame* pSectionLower = pTmpFrame->GetLower())
+                        {
+                            if (!pSectionLower->IsColumnFrame())
+                                // Section has a single column only, try to
+                                // split that.
+                                bRet = false;
+                        }
+                    }
+                }
             }
 
             if ( bRet )