avoid CELLTYPE_EDIT for calc's threaded calculations

Since ScEditUtils::GetString() requires EditEngine, which is probably not
completely thread-safe.

Change-Id: Ie3d64f56b76a5861fa4b0a1f9cb683cd26806b35
Reviewed-on: https://gerrit.libreoffice.org/54766Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
Tested-by: Michael Meeks <michael.meeks@collabora.com>

sc/source/core/data/column2.cxx

@@ -2823,6 +2823,9 @@ bool ScColumn::HandleRefArrayForParallelism( SCROW nRow1, SCROW nRow2 )
         auto aCell = GetCellValue(i);
         if (aCell.meType == CELLTYPE_FORMULA)
             aCell.mpFormula->MaybeInterpret();
+        // These require EditEngine (in ScEditUtils::GetString()), which is probably too complex for use in threads.
+        if (aCell.meType == CELLTYPE_EDIT)
+            return false;
     }
 
     return true;