run: set GOENV=off when running 'go tool dist env'
'go tool' sets environment variables, including the GOAMD64 value
from the user's go.env file.
'go tool dist test' then rebuilds and reinstalls the toolchain and
standard library based on those variables. It should not; instead, it
should test exactly the configuration installed by the make scripts.
Fixes #54084.
Change-Id: I7cc8a21cc1d8331e06d7b7c55b14d170f8e2faab
Reviewed-on: https://go-review.googlesource.com/c/go/+/420055
Run-TryBot: Bryan Mills <bcmills@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com>