x/build: skip darwin-386-10_14 builder on release-branch.go1.12

[bcmills]

As far as I can tell, the darwin-386-10_14 builder was added for #31751 and has been failing for release-branch.go1.12 ever since.

I doubt we'll want to fix a deprecated architecture on an old Go version, so we should skip the builder in that configuration instead.

CC @golang/osp-team

[toothrot]

I can take a look into this.

[toothrot]

@bcmills Do you think that we should build on >= 1.13, or only master?

[bcmills]

The underlying bug was fixed in 1.13, so this builder should run everything ≥ 1.13.

[gopherbot]

Change https://golang.org/cl/191878 mentions this issue: dashboard: require at least Go 1.13 for darwin-386 builder

[toothrot]

I will re-deploy the coordinator and build.golang.org to pick up this change.

[bcmills]

@dmitshur, I notice that this builder is currently showing up in the build dashboard for release-branch.go1.12. I assume that's an expected wart after https://golang.org/cl/199878 (with the fix gated on the app/appengine / cmd/coordinator cleanup)?

[dmitshur]

@bcmills That is correct.

I think it is a low priority enough wart that it can wait a few weeks (compared to the master branch of the main Go repo, I didn't think that could wait as long), but let me know if you think it's more disruptive and should be fixed sooner.