Doxygen code style

[Roman Gilg]

Commit
https://phabricator.kde.org/R108:7b20e1f66f83657591001f473d31555c295e5569
changes Doxygen comments style in KWin to the uniform pattern

/**
 *
 **/

with two stars at the end.

Looking at upstream examples
http://www.doxygen.nl/manual/docblocks.html#cppblock
online examples
https://mesos.readthedocs.io/en/latest/doxygen-style-guide/
other projects
https://gitlab.freedesktop.org/dbus/dbus/blob/master/dbus/dbus-connection.h
and KDE frameworks
https://cgit.kde.org/kio.git/tree/src/core/copyjob.h
the preferred style though is

/**
 *
 */

with one star at the end.

With one notable exception: KWayland, where the two-star pattern is
used consistently.
Also plasma-framework does mix both styles:
https://cgit.kde.org/plasma-framework.git/tree/src/plasma/package.h

I would like to uniformly use the one-star at the end pattern in
KWin/KWayland and our other projects like upstream Doxygen suggests
and other projects seem to adhere to most often, but want to get other
opinions on that first.

Cheers,
Roman