cmd/compile: racecompile builder failures on multiple packages #28170
Description
The racecompile builder has been very flaky for the past two days:
failures are reported on many different packages:
https://build.golang.org/log/706e3c506500ddd44b3c7f2a303aff6dc2d415f3
https://build.golang.org/log/68197029863f12197c4d34d1f7eb5a9eec553176
https://build.golang.org/log/eb23684cf4d9315e388a78d84f972daaa1a8b9ee
https://build.golang.org/log/e71a2d04359d9b57b7aa6725ce03edbbcaad9f03
and others. The first failure happened right after https://go-review.googlesource.com/c/go/+/140698 was committed.
cc @randall77