Revert "Running 'pip install --upgrade setuptools' with 'sudo' on mac…

…OS, fixing pypa#122"

This reverts commit d79ca07.
pip has been fixed in 19.0.2

cibuildwheel/macos.py

@@ -86,8 +86,7 @@ def call(args, env=None, cwd=None, shell=False):
  # install pip & wheel
  call(['python', get_pip_script, '--no-setuptools', '--no-wheel'], env=env)
  call(['pip', '--version'], env=env)
- # sudo required, because the removal of the old version of setuptools might cause problems with newer pip versions (see issue #122)
- call(['sudo', 'pip', 'install', '--upgrade', 'setuptools'], env=env)
+ call(['pip', 'install', '--upgrade', 'setuptools'], env=env)
  call(['pip', 'install', 'wheel'], env=env)
  call(['pip', 'install', 'delocate'], env=env)