rtapi/vs_ring_write: shorten critical section
rtapi/vs_ring_write: shorten critical section

Previously, vs_wring_write used zero-copy formatting directly into the
ringbuffer. This means the critical section is fairly long (the duration
of the format operation).

Use a copying write ringop to shorten the critical section.

RunningLight/machinekit,unseenlaser/machinekit,mhaberler/machinekit,mhaberler/machinekit,ArcEye/MK-Qt5,EqAfrica/machinekit,kinsamanka/machinekit,ArcEye/machinekit-testing,EqAfrica/machinekit,strahlex/machinekit,RunningLight/machinekit,araisrobo/machinekit,araisrobo/machinekit,kinsamanka/machinekit,Cid427/machinekit,bobvanderlinden/machinekit,araisrobo/machinekit,unseenlaser/machinekit,Cid427/machinekit,ArcEye/MK-Qt5,strahlex/machinekit,strahlex/machinekit,unseenlaser/machinekit,araisrobo/machinekit,ArcEye/MK-Qt5,Cid427/machinekit,mhaberler/machinekit,mhaberler/machinekit,EqAfrica/machinekit,RunningLight/machinekit,Cid427/machinekit,kinsamanka/machinekit,Cid427/machinekit,araisrobo/machinekit,kinsamanka/machinekit,mhaberler/machinekit,EqAfrica/machinekit,RunningLight/machinekit,Cid427/machinekit,bobvanderlinden/machinekit,bobvanderlinden/machinekit,mhaberler/machinekit,EqAfrica/machinekit,ArcEye/MK-Qt5,ArcEye/MK-Qt5,kinsamanka/machinekit,kinsamanka/machinekit,bobvanderlinden/machinekit,strahlex/machinekit,ArcEye/machinekit-testing,kinsamanka/machinekit,mhaberler/machinekit,ArcEye/machinekit-testing,unseenlaser/machinekit,bobvanderlinden/machinekit,EqAfrica/machinekit,ArcEye/machinekit-testing,strahlex/machinekit,Cid427/machinekit,ArcEye/MK-Qt5,unseenlaser/machinekit,RunningLight/machinekit,bobvanderlinden/machinekit,strahlex/machinekit,RunningLight/machinekit,araisrobo/machinekit,mhaberler/machinekit,Cid427/machinekit,EqAfrica/machinekit,unseenlaser/machinekit,unseenlaser/machinekit,ArcEye/machinekit-testing,RunningLight/machinekit,strahlex/machinekit,araisrobo/machinekit,araisrobo/machinekit,RunningLight/machinekit,ArcEye/MK-Qt5,bobvanderlinden/machinekit,kinsamanka/machinekit,ArcEye/machinekit-testing,ArcEye/machinekit-testing,araisrobo/machinekit,ArcEye/MK-Qt5,unseenlaser/machinekit,ArcEye/machinekit-testing,bobvanderlinden/machinekit,EqAfrica/machinekit