handle 0 width tables gracefully

sw/source/filter/ww8/ww8par2.cxx

@@ -2239,6 +2239,8 @@ void WW8TabDesc::CalcDefaults()
                 }
             }
         }
+        if (pR->nWwCols)
+        {
             /*
             Similiar to graphics and other elements word does not totally
             factor the width of the border into its calculations of size, we
@@ -2276,6 +2278,7 @@ void WW8TabDesc::CalcDefaults()
                     nLeftMaxThickness = nThickness;
             }
         }
+    }
     nSwWidth = nSwWidth + nRightMaxThickness;
     nMaxRight = nMaxRight + nRightMaxThickness;
     nConvertedLeft = nMinLeft-(nLeftMaxThickness/2);