encode: fix warnings about precedence
encode: fix warnings about precedence

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