I've received a report from an Android user with a gamepad (a "BSP-D3")
where one physical trigger is controlling two analog axes at the same
time. This was causing RemoveSpuriousTriggerCombinations to delete both
axes, which is clearly not a desireable outcome.
With this change, now the axis with the greatest smoothness is kept,
or both in case they have the same smoothness.
71ac6ec239