cmd/search: add Arch Linux
cmd/search: add Arch Linux

Arch update their packages very quickly, so they're quite useful as a
reference for building formulae.

JCount/brew,MikeMcQuaid/brew,EricFromCanada/brew,Homebrew/brew,JCount/brew,Homebrew/brew,MikeMcQuaid/brew,MikeMcQuaid/brew,nandub/brew,EricFromCanada/brew,MikeMcQuaid/brew,Homebrew/brew,JCount/brew,EricFromCanada/brew,EricFromCanada/brew,nandub/brew,JCount/brew,Homebrew/brew,nandub/brew,nandub/brew