Populate compile_time_autotune_time_us (#143104)
Summary:
See testing in attached diff
X-link: https://github.com/pytorch/pytorch/pull/143104
Approved by: https://github.com/ezyang
Reviewed By: clee2000
Differential Revision: D67128210
Pulled By: masnesral
fbshipit-source-id: 5c7f5f98db7f4768127d61e7bcefef39b51a064c
