mysqld_safe is the recommended way to start the server on non-systemd
systems ([1]). For instance, it has a crash detection with auto-restart
function, can update ulimits, setup core files, set the niceness of the
server etc. It looks like it could also be helpful when trying to set up
clusters. It's maintained upstream and adding it means we don't need to
add these features into our init script.

mysqld_safe is a script itself, so it's added to conffiles in case users
want to edit it.

It can't be run under procd, so the init script is converted to a normal
System V type. To stop the server and to reload the privileges tables
mysqladmin is used. To that end mysqladmin is moved into the server
package.

While changing the init script, the Debian init script was used for
ideas. It wasn't copied verbatim and adapted a bit here and there.
Thanks to whoever wrote it!

This commit removes the support for starting the service as a user other
than "mariadb". This makes the init script simpler. If anybody wants to
play around with the user then it's up to them to fix the permissions.

[1] https://mariadb.com/kb/en/mysqld_safe/

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>

Highlights:

- Bump from 10.2.26 to 10.4.10
- auth_pam got replaced with never version, old one still available as
  auth_pam_v1
- semisync plugins were merged into the core
- Upstream now installs symlinks for binaries with mariadb prefix. To
  accommodate that this commit updates Package/mariadb/install/bin
  accordingly.
- Patches are updated with new ones from Debian and Arch (thanks!)
- libedit patch dropped because it's upstream now.

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>

- added trailing '--' to logger to make it foolproof
- user is extracted from config instead of using hard-coded value
- log directory is now also extracted from config (if set)
- directory creation is now done via awk script (more robust)
- improved log messages

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>

Does away with /etc/default/mysqld, introduces uci configuration
instead. The init script receives some further brushing up, like a
function (copied from Debian) to get mysqld configuration parameters
easily and quickly.

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>

Also create a user "mariadb" and use it for running the server. And
add possibility to easily add command line args.

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>

- create directory /etc/mysql/conf.d as without it the server refuses to
  start
- correct the path to my.cnf in the init script

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>

MariaDB is a drop-in replacement for MySQL. This commit adds a current
and stable version of MariaDB to the tree.

Quite a few ideas/patches were copied from Alpine Linux, Busybox Buildroot
and Debian.

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>