Start by adding them as post-submit builders, only in the main Go repo,
and only at tip. Mostly so it's easier to see the generated code and
iterate. Once they work, they'll be turned up in the remaining places.

For golang/go#61116.
For golang/go#61117.

Change-Id: I72127713d1043acc800b2fc13a0fcccdf090aeba
Reviewed-on: https://go-review.googlesource.com/c/build/+/538897
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
TryBot-Bypass: Dmitri Shuralyov <dmitshur@golang.org>

The wazero and wasmtime packages are available in infra/3pp/tools as
of crrev.com/c/4995549. In preparation of the switch soon to be done
in crrev.com/c/4995558, prepend the "2@" package epoch (more context
in crrev.com/c/2763964) that their version strings ended up with.

Also factor out the comment explaining how to check the availability
of a given version in CIPD, so we don't need to repeat it 3 times.

For golang/go#61116.
For golang/go#61117.

Change-Id: I1c638aec1782b8d4f15724c0acc97f0323e5f70a
Reviewed-on: https://go-review.googlesource.com/c/build/+/539715
TryBot-Bypass: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Bypass: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

The GOOS=wasip1 port is new to Go 1.21, so there's nothing to test
on release-branch.go1.20.

I'll also likely need to backport a test-only version of CL 539435
for it to work.

For golang/go#61116.
For golang/go#61117.

Change-Id: I53d0b370a98059f2f4f721402a9e0f153df4f28b
Reviewed-on: https://go-review.googlesource.com/c/build/+/539417
TryBot-Bypass: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>

For golang/go#61116.
For golang/go#61117.

Change-Id: I90898bb976009086a617d56348becb5d9bdc747f
Reviewed-on: https://go-review.googlesource.com/c/build/+/539418
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Bypass: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

This is the last step after turning it on in postsubmit everywhere.

In the old build system, we've decided that just one of the multiple
wasip1 builders is enough signal for trybots. We could propagate that
decision here by putting wasip1-wasm_wazero (not wasip1-wasm_wasmtime)
in some "don't include in pre-submit" list, but for now we choose to
defer that kind of policy and configuration complexity until there's
a concrete need.

Fixes golang/go#61116.
Fixes golang/go#61117.

Change-Id: I54403eaf299f4c9a3d68f350323763670663f1b0
Reviewed-on: https://go-review.googlesource.com/c/build/+/539419
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Bypass: Dmitri Shuralyov <dmitshur@golang.org>