mcenc: fix warnings about precedence
mcenc: fix warnings about precedence

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