Selafin: avoid Open() in update mode on /vsizip/ directories to open them even if they are not selafin related

git-svn-id: https://svn.osgeo.org/gdal/trunk@27598 f0d54148-0727-0410-94bb-9a71ac55c965
/vsizip/ on >4GB zips: accept .zip declare 0 disks (#5615)

git-svn-id: https://svn.osgeo.org/gdal/trunk@27599 f0d54148-0727-0410-94bb-9a71ac55c965