[Bug 35815] Allow remapping of joystick buttons

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=35815

--- Comment #20 from Rémi Bernon  ---
Well sure I didn't say it would not be possible to do some DInput-only
remapping, just that it would not be ideal imho as it will only apply to
DInput, and applications using another way to access the device will not see
any mapping change.

I believe SDL_GAMECONTROLLERCONFIG could work, and its use is not XInput
specific anymore. There may be some details to sort out here, as it only works
if SDL exposes a "controller" device, but I believe that variable can actually
make it do just that (force creation of a mapping from a SDL joystick to a SDL
controller).