Remove build-only dependency on curl / libzip
Remove build-only dependency on curl / libzip

Unfortunately, due to dynamic linking, both curl and libzip are required at runtime.
See https://bot.brew.sh/job/Homebrew%20Core%20Pull%20Requests/7439/version=el_capitan/testReport/brew-test-bot/el_capitan/test_tldr/ for a failed CI build.
tldr-pages/homebrew-tldr