Fix benchmark_runner.py.
Fix benchmark_runner.py.

(the order of parameters in the Paths constructor has changed,
apparently)

R=qsr@chromium.org

Review URL: https://codereview.chromium.org/1250743006 .

afandria/mojo,afandria/mojo,afandria/mojo,afandria/mojo,afandria/mojo,afandria/mojo,afandria/mojo,afandria/mojo