This check seems to apply to all code instrumentation, not just -race.

Fixes #14589.

Change-Id: I16ae07749ede7c1e6ed06f472711638d195034ac
Reviewed-on: https://go-review.googlesource.com/20113
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Marvin Stenger <marvin.stenger94@gmail.com>