This will allow us to cut the build-time for things in half.
Unfortunately, this may also mean we break users who use non-homebrew-php php's. I'm of the opinion that if there are such users, I can safely force them to install using the --universal flag.
Please see Homebrew/legacy-homebrew#14009 for further details. This will not be merged in until I can confirm that this won't break 25345 installations.
If you tap this branch, I WILL hurt you.
Never build universal binaries by default
Please merge this. Extensions simply cannot build with universal enabled. For example solr (#321) and oauth.