Is gdb itself always universal or is it an option? If the latter is the case, we might use `option :universal`
Usually (inside of the install method) we specify `ENV.universal_binary if build.universal?`. Not sure if we should do this for gdb, though.

If you only need python to be universal, you might have a look at the `boost149` formula in homebrew-core.

```ruby
class UniversalPython < Requirement
  satisfy { archs_for_command("python").universal? }

  def message; <<-EOS.undent
    A universal build was requested, but Python is not a universal build

    Boost compiles against the Python it finds in the path; if this Python
    is not a universal build then linking will likely fail.
    EOS
  end
end

class Gdb < Formula
  ...
  depends_on UniversalPython
```