Fixed-wing autoland: ALWAYS flare when close to the ground, independently of...

Fixed-wing autoland: ALWAYS flare when close to the ground, independently of the horizontal distance to the land WP. This avoids that we crash into the ground at negative pitch and guarantees that the flare always starts at the same altitude above ground. However, the motor shutoff still depends on the horizontal distance to the LAND WP, thus avoiding that the motor is shut off prematurely