afl-eventtesting: div by zero

Change-Id: If070da723858b5e1221bda86e69225ee57ec9d02
(cherry picked from commit cfcf0254)
Reviewed-on: https://gerrit.libreoffice.org/19467Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>

svtools/source/control/valueset.cxx

@@ -1327,7 +1327,7 @@ void ValueSet::KeyInput( const KeyEvent& rKeyEvent )
             {
                 if (nCurPos == nLastItem)
                 {
-                    const size_t nCol = nLastItem % mnCols;
+                    const size_t nCol = mnCols ? nLastItem % mnCols : 0;
                     if (nCol < mnCurCol)
                     {
                         // Move to previous row/page, keeping the old column