c:delete is true by default in Excel

One step closer to opening my simple test file correctly in Excel.

Change-Id: I1bfa76a46081ba478e44d8d90d8a91790a9a9ff3
(cherry picked from commit 6ddd7fcc)
Reviewed-on: https://gerrit.libreoffice.org/3685Reviewed-by: Kohei Yoshida <kohei.yoshida@suse.de>
Tested-by: Kohei Yoshida <kohei.yoshida@suse.de>

oox/source/export/chartexport.cxx

@@ -2084,13 +2084,9 @@ void ChartExport::_exportAxis(
             OUString ("Visible")) >>=  bVisible;
     }
 
-    if( !bVisible )
-    {
-        // other value?
-        pFS->singleElement( FSNS( XML_c, XML_delete ),
-            XML_val, "1",
+    pFS->singleElement( FSNS( XML_c, XML_delete ),
+            XML_val, bVisible ? "0" : "1",
             FSEND );
-    }
 
     // FIXME: axPos, need to check the property "ReverseDirection"
     pFS->singleElement( FSNS( XML_c, XML_axPos ),