SDL2's concept of GameController is a like a PS or Xbox controller, two sticks, four face buttons, etc. These are the same as the bgfx example's Gamepad.
SDL also has a concept of Joystick, which could be anything, like a flight stick. Game Controllers are implemented by these lower level joystick's.
Entry SDL gets duplicate events, for both controller and the joystick implementing it. Game controller buttons are remapped to bgfx gamepad, but joystick buttons are not. This causes incorrect button presses.
Additionally, the joystick z axis behaves differently than game controller or bgfx gamepad. With at-rest value being negative, not zero.
Due to all of this, it seems like the best approach would be to ignore joystick events and only handle game controller events.
Also, minor additional fix to get handle's index when using it as array index. Fixes compilation in Visual Studio.
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