Picks the first Xinput device available, waits 100 frames between
retries when no devices are available.
Controls are hardcoded so every x360 controller button corresponds
to the PSP button in the same physical position. Input from right
stick and from analog triggers is ignored.
The Xinput code though is overriden by SampleControls' hardcoded
keyboard input. XinputDevice was tested to work with
samples/controller/basic when SampleControls is disabled.