[horde] Blank configuration tabs

[Jaap Winius]

Citing Arjen de Korte build+horde at de-korte.org, Tue May 14 19:51:51  
UTC 2019:

> Sounds more like a permissions problem. Are you sure everything is   
> readable by whoever PHP/webserver is running as?

It doesn't look like it. The web server user is www-data and that user  
also owns all of /etc/horde as well as /var/cache/horde/static and  
/var/cache/apache2/mod_cache_disk. It's the same on both machines.

Thanks anyway,

Cheers,

Jaap