Mir Licensing

[Ma Xiaojun]

Someone expressed concerns about Mir (at least the server library)
being GPLv3 only [1] . I find [1] non-sense in most parts but the
"License" seems a bit reasonable, copy & paste here.

"""
Wayland is licensed like X under the MIT license, which served us well
for a display server. I think this is a very good choice and I am glad
that the Wayland developers decided for this license. Mir is licensed
under GPLv3-only with CLA. I think this is very unsuited for such a
part of the stack and would render quite a risk for usage in KDE
Plasma. KWin (and most KDE software) is GPLv2-or-later, this would no
longer be possible, it would turn our code into GPLv3-only as KWin (or
any other software which would depend on mir-server) would be a
derived work of Mir. I do not consider GPLv3-only software as a
possible dependency of any core part of our application stack. It
renders a serious threat for the future in case of a GPLv4 which is
not compatible with GPLv3. I also dislike the CLA [6]. So from a
licensing perspective Mir is hardly acceptable.
"""

The solution should be simple. Change from GPLv3 to GPLv3+ and no one
should complain MIr licensing issue any more.

1. http://blog.martin-graesslin.com/blog/2013/05/mir-in-kubuntu/