Move q10 calculation to initialisation. (#999)
Move q10 calculation to initialisation. (#999)

Pull out a constant computation from the update function to the initialisation step in the HH mechanism. In the busyring benchmark with hh/pas swapped this results in an overall speed-up
of roughly 20%.
halfflat/nestmc-proto,halfflat/arbor,halfflat/arbor,halfflat/arbor,eth-cscs/nestmc-proto,halfflat/nestmc-proto,halfflat/arbor,halfflat/arbor,eth-cscs/nestmc-proto,halfflat/nestmc-proto,eth-cscs/nestmc-proto