akonadi has undocumented delta with debian package

[Harald Sitter]

  * Merge with debian experimental, remaining changes:
    - Add a mysqld-akonadi wrapper script.
    - Add apparmor profile for mysqld-akonadi (usr.sbin.mysqld-akonadi).
    - Make akonadi-backend-mysql depend on mysql-server-core-5.5 and
      mysql-client-core-5.5 instead of mysql-server-core.
    - Force dependency on akonadi-backend-mysql for akonadi-server.

of those changes
- the wrapper script is there because we don't like copying stuff, however it appears debian does not copy stuff either, so why is it there
- apparmor is there because we like apparmor, and have a wrapper script (see above)
- the depdency changes on the mysql backend are of unknown origin as they predate bzr branches and are not documented in the changelog
- the dependency from server to mysql exclusively is also of unknown origin and doesn't even make any sense

all the rubbish must be evaluated and (supposedly) the entire delta can then be dropped.

real life implications of the delta:
- cannot install mysql drop-in replacements such as mariadb and what have you
- cannot not have mysql backend installed
- because of that cannot not have mysql installed

[Philip Muškovac (yofel)]

apparmor:
we ship an apparmor profile because the mysql system profile doesn't permit accessing ~/.local/share/akonadi, which we need. But because you can't (couldn't?) just extend a profile, we're shipping a wrapper script which uses our profile.

mysql deps:
here it gets complicated...
The hard-depend on akonadi-backend-mysql is there because we had cases in the past where issues with mysql would result in the backend getting switched out with another one (usually sqlite) by apt. As akonadi doesn't actually support that though without manual reconfiguring, it just tells uses that their mysql backend is broken, which isn't helpful at all. The workaround is a fixed dep on a-b-m so that never gets removed, which is bad but does the job...

The fixed versioned deps on explicit versions of mysql where there to prevent bogus downgrades to unsuppored mysql versions I think (at least that's the only reason I could think of, as that's indeed not documented). We should depend on virtual-mysql-server-core and virtual-mysql-client-core instead. That has the downside of again allowing incompatible DB software migrations by apt (e.g. mariadb -> mysql) but that's already the case with our alternate dep on mariadb. Would fix #1336005 at least