pvq: use od_beta_rcp in od_gain_compand
pvq: use od_beta_rcp in od_gain_compand

No change in metrics.

luctrudeau/daala,xiph/daala,ycho/daala,xiph/daala,xiph/daala,luctrudeau/daala,xiph/daala,ycho/daala,xiph/daala,luctrudeau/daala,ycho/daala,ycho/daala,ycho/daala,luctrudeau/daala,luctrudeau/daala