Acceleration structures in the viewport default to building with the fast
build flag, but the intersection program used for curves was queried with
the fast trace flag. The resulting mismatch caused an exception in the
intersection kernel. Since it's difficult to predict whether dynamic or static
acceleration structures are going to be built at the time of kernel loading,
this fixes the mismatch by always using the fast trace flag for curves.
Patrick Mours
5c6053ccb1