dashboard: add plan9-386-0intro builder

This change adds the plan9-386-0intro builder
configuration.

Updates golang/go#29801.

Change-Id: I5f64f4592a499eb1691498805fd0dfa5082c33d5
Reviewed-on: https://go-review.googlesource.com/c/build/+/175901
Run-TryBot: David du Colombier <0intro@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

dashboard/builders.go

@@ -282,6 +282,11 @@ var Hosts = map[string]*HostConfig{
 		ExpectNum:   1,
 		OwnerGithub: "0intro",
 	},
+	"host-plan9-386-0intro": &HostConfig{
+		IsReverse:   true,
+		ExpectNum:   1,
+		OwnerGithub: "0intro",
+	},
 	"host-plan9-386-gce": &HostConfig{
 		VMImage:            "plan9-386-v7",
 		Notes:              "Plan 9 from 0intro; GCE VM is built from script in build/env/plan9-386",
@@ -2195,6 +2200,23 @@ func init() {
 		},
 		buildsRepo: onlyMaster,
 	})
+	addBuilder(BuildConfig{
+		Name:         "plan9-386-0intro",
+		HostType:     "host-plan9-386-0intro",
+		SkipSnapshot: true,
+		shouldRunDistTest: func(distTestName string, isTry bool) bool {
+			if !noTestDir(distTestName, isTry) {
+				return false
+			}
+			switch distTestName {
+			case "api",
+				"go_test:cmd/go": // takes over 20 minutes without working SMP
+				return false
+			}
+			return true
+		},
+		buildsRepo: onlyMaster,
+	})
 	addBuilder(BuildConfig{
 		Name:             "aix-ppc64",
 		HostType:         "host-aix-ppc64-osuosl",