class Gem::BasicSpecification

On universal Rubies, resolve the “universal” arch to the real CPU arch, without changing the extension directory.

def extensions_dir 

def extensions_dir
  @extensions_dir ||=
    Gem.default_ext_dir_for(base_dir) || File.join(base_dir, "extensions", ORIGINAL_LOCAL_PLATFORM, Gem.extension_api_version)
end