Resolves: tdf#123052 correctly init pNextRows[] values for up/back unprotected

Regression from

    commit ec68d58a
    CommitDate: Fri Jul 6 14:25:07 2018 +0200

        GetNextPos: deduplicate some nMovX code

Change-Id: I0352d44eda587d2c340df4c7d8fe35b7b8591fc1
Reviewed-on: https://gerrit.libreoffice.org/67693Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Jenkins

sc/source/core/data/table1.cxx

@@ -1523,8 +1523,16 @@ void ScTable::GetNextPos( SCCOL& rCol, SCROW& rRow, SCCOL nMovX, SCROW nMovY,
             const SCROW nRowAdd = (bUp ? -1 : 1);
             sal_uInt16 nWrap = 0;
 
-            for (SCCOL i = 0; i < nColCount; ++i)
-                pNextRows[i] = (i + nStartCol < nCol) ? (nRow + nRowAdd) : nRow;
+            if (bUp)
+            {
+                for (SCCOL i = 0; i < nColCount; ++i)
+                    pNextRows[i] = (i + nStartCol > nCol) ? (nRow + nRowAdd) : nRow;
+            }
+            else
+            {
+                for (SCCOL i = 0; i < nColCount; ++i)
+                    pNextRows[i] = (i + nStartCol < nCol) ? (nRow + nRowAdd) : nRow;
+            }
             do
             {
                 SCROW nNextRow = pNextRows[nCol - nStartCol] + nRowAdd;