Matt Harbison <matt_harbison@yahoo.com> [Mon, 30 Dec 2019 23:53:53 -0500] rev 44017
py3: replace `time.clock()` with `time.perf_counter()`
The former was removed in 3.8. The util function uses `time.clock()` if the
latter is unavailable.
Differential Revision: https://phab.mercurial-scm.org/D7779