bnc#520828: Correctly import fields with same name in excel's pivot tables.

We just need to append '2' on the 2nd field with identical name, not '1'.
This alone fixes the import problem.

sc/source/core/data/dptablecache.cxx

@@ -654,8 +654,7 @@ void ScDPCache::AddLabel(ScDPItemData *pData)
             if (maLabelNames[i].maString.equals(strNewName))
             {
                 strNewName = pData->maString;
-                strNewName += String::CreateFromInt32( nIndex );
-                ++nIndex;
+                strNewName += String::CreateFromInt32( ++nIndex );
                 bFound = true;
             }
         }