posemath: fixed PM_CARTESIAN cross product
posemath: fixed PM_CARTESIAN cross product

The cross product was returning garbage due to being passed the same
pointer for both input and output. Now, the output vector is separate so
there is no overlap.

Signed-off-by: Robert W. Ellenberg <7cf60555c449d119e88c087cd5eb42ff6272cb3e@gmail.com>

ikcalB/linuxcnc-mirror,ikcalB/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror,ikcalB/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror,ikcalB/linuxcnc-mirror,ikcalB/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror,ikcalB/linuxcnc-mirror,ikcalB/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror