[linux] Upgrade SDL1.2 to SDL2 for hotpluggable joysticks

This is a set of patches that cleans up some of the CJoystick mess and makes it use SDL2 which brings hotplug support without udev hacks.

This PR continues @topfs2' work (in https://github.com/topfs2/xbmc/tree/sdl2) of moving to SDL2 for linux joystick handling. It is also a followup of https://github.com/xbmc/xbmc/pull/5357 which cleans up some of the joystick mess which made the transition to SDL2 less painful.
Can tuple be forward declared?
On Sep 14, 2014 2:36 PM, "Rainer Hochecker" <notifications@github.com>
wrote:

> In xbmc/input/ButtonTranslator.h:
>
> > @@ -26,6 +26,7 @@
> >  #include <map>
> >  #include <string>
> >  #include <vector>
> > +#include <boost/tuple/tuple.hpp>
>
> ButtonTranslator.h is included by many other files. All those files will
> get the entire boost clutter which is not desired. This can slow down build
> times tremendously.
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/xbmc/xbmc/pull/5364/files#r17519220>.
>