Suggested akonadi backports for 18.12

[David Faure]

Notice for distributions shipping 18.12 as a stable version (which I think is 
at least the case for OpenSuSE and Ubuntu) :

I strongly suggest to apply commits 
https://commits.kde.org/akonadi/15c91a0ac93051465b37807efceb6e9fd36cb73b
https://commits.kde.org/akonadi/4fb179ce46ad3e7da8b25c921b0c8a68f9dfb4ee
which I just backported from 19.04 to 18.12 git branch.

This fixes bug https://bugs.kde.org/show_bug.cgi?id=399167 which seems to hit 
many people rather badly -- akonadi won't answer to any requests once hitting 
that bug, and even a reboot only help very temporarily (until the faulty 
folder gets synced again).

These fixes from April have proven stable by now, i.e. no regressions have 
been detected.

Fabian: a package for OpenSuSE Leap 15.1 Update is ready at
https://build.opensuse.org/package/show/home:dfaure/akonadi-server

-- 
David Faure, faure at kde.org, http://www.davidfaure.fr
Working on KDE Frameworks 5