[fix] circle-count without rewinding when flying in opposite direction

bugfix:

When polygons or landings are triggered at the "wrong time"** then NavCircleCount() > 0.1 causes the plane to make 2 full circles.

** e.g. polygonsurvey of 1234 rectangle is started when in the prolongation of 1-2
** the plane accidentally can not make it right of the center with a counterclockwise circle, then first -180 degrees are integrated in NavCircleCount, then afterwards you need 180 deg extra CircleCount, often resulting in 1 unnecerray circle