cmd/dist,internal/testdir: more cooperative host test mechanism
On cross-compiling builder machines, we run internal/testdir on the
host, where it can access the Go toolchain to build binaries for the
guest and run them through an exec wrapper. Currently this uses dist
test's existing host test mechanism, which is quite complicated and we
are planning to eliminate (#59999).
Switch internal/testdir to use a more cooperative mechanism. With this
CL, dist still understands that it has to build and run the test using
the host GOOS/GOARCH, but rather than doing complicated manipulation
of environment variables itself, it passes the guest GOOS/GOARCH to
the test, which can easily inject it into its environment. This means
dist test can use "go test" directly, rather than having to split up
the build and run steps.
For #37486.
Change-Id: I556938c0b641960bb778b88b13f2b26256edc7c9
Reviewed-on: https://go-review.googlesource.com/c/go/+/492985
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>