Add high bit depth support to dump_msssim.
Add high bit depth support to dump_msssim.

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