x/build: add LUCI wasip1-wasm32_wasmtime builder

[johanbrandhorst]

As part of the work on the wasm32 architecture, we'd like to add a new builder for running the wasip1 tests. This builder will need to have wasmtime installed and set the following environment variables:

GOOS=wasip1
GOARCH=wasm
GOWASIRUNTIME=wasmtime
PATH=$PATH:/workdir/go/misc/wasm
GO_DISABLE_OUTBOUND_NETWORK=1

CC @dmitshur

[johanbrandhorst]

CC @golang/wasm

[dmitshur]

Thanks. Confirming a few details.

GOARCH should be wasm32 instead of wasm, is that right?

Related to the above—will GOROOT/misc/wasm be used for both wasm and wasm32 exec helpers? That seems good to me, just confirming.

GO_DISABLE_OUTBOUND_NETWORK is an internal implementation detail of the old build system, no need to set it for this builder in LUCI.

If the above is right, the definition of this builder in main.star will be very similar to the wasip1-wasm_wasmtime builder. There'll be a few places to consider wasm32 architecture value in addition to wasm, both in main.star (e.g., here and here) and in golangbuild (e.g., here), maybe by checking for their common "wasm" prefix.

[johanbrandhorst]

GOARCH should be wasm32 instead of wasm, is that right?

Yes

Related to the above—will GOROOT/misc/wasm be used for both wasm and wasm32 exec helpers? That seems good to me, just confirming.

Yes

GO_DISABLE_OUTBOUND_NETWORK is an internal implementation detail of the old build system, no need to set it for this builder in LUCI.

OK, great, I was unsure about that one.