dump_psnrhvs: fix -Wabsolute-value
dump_psnrhvs: fix -Wabsolute-value

Fixes "using floating point absolute value function 'fabs'
when argument is of integer type".

KyleSiefring/daala,jmvalin/daala,xiphmont/daala,xiphmont/daala,ycho/daala,ycho/daala,jmvalin/daala,jmvalin/daala,jmvalin/daala,xiph/daala,KyleSiefring/daala,luctrudeau/daala,KyleSiefring/daala,luctrudeau/daala,ycho/daala,ycho/daala,xiph/daala,KyleSiefring/daala,HeadhunterXamd/daala,HeadhunterXamd/daala,luctrudeau/daala,xiph/daala,xiph/daala,HeadhunterXamd/daala,xiphmont/daala,xiphmont/daala,xiphmont/daala,luctrudeau/daala,ycho/daala,luctrudeau/daala,jmvalin/daala,xiph/daala,HeadhunterXamd/daala,HeadhunterXamd/daala,KyleSiefring/daala