volk 2.5.1
volk 2.5.1

Also, use Homebrew `cpu_features`.

We restrict this to Intel, since `cpu_features` hasn't been bottled on
ARM.

zyedidia/homebrew-core,chrisfinazzo/homebrew-core,makigumo/homebrew-core,filcab/homebrew-core,cblecker/homebrew-core,makigumo/homebrew-core,zyedidia/homebrew-core,uyjulian/homebrew-core,lemzwerg/homebrew-core,lemzwerg/homebrew-core,stgraber/homebrew-core,chrisfinazzo/homebrew-core,nandub/homebrew-core,adam-moss/homebrew-core,stgraber/homebrew-core,nandub/homebrew-core,Homebrew/homebrew-core,Homebrew/homebrew-core,sjackman/homebrew-core,sjackman/homebrew-core,nbari/homebrew-core,adam-moss/homebrew-core,cblecker/homebrew-core,filcab/homebrew-core,nbari/homebrew-core,uyjulian/homebrew-core