cmd/dist: pass a -test.timeout option to a host test
For a host test we build the test using "go test -c" and then run the
test binary. A test binary run in this way has no default timeout.
This CL gives it a timeout of 5 minutes, scaled for the target.
We can adjust the timeout if necessary.
For #52998
Change-Id: Ib759142f3e71cbb37ec858182998fc5d4fba7ab6
Reviewed-on: https://go-review.googlesource.com/c/go/+/407374
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Michael Knyszek <mknyszek@google.com> Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>