tdf#118153 VBA Macro: add XLSX support to Workbooks.Open

by accepting "MS Excel 2007 XML" in isSpreadSheetFile().

Test example:

Workbooks.Open Filename:="/tmp/test.xlsx"

Change-Id: Id7102325c96842bb413b1fb7bb8162e8bca41f4e
Reviewed-on: https://gerrit.libreoffice.org/57030Reviewed-by: László Németh <nemeth@numbertext.org>
Tested-by: László Németh <nemeth@numbertext.org>

sc/source/ui/vba/vbaworkbooks.cxx

@@ -169,6 +169,7 @@ ScVbaWorkbooks::isSpreadSheetFile( const OUString& sType )
 {
     // include calc_QPro etc. ? ( not for the moment anyway )
     return sType.startsWith( "calc_MS" )
+      || sType.startsWith( "MS Excel" )
       || sType.startsWith( "calc8" )
       || sType.startsWith( "calc_StarOffice" );
 }