gopls/internal/regtest: skip builders on which regtests time out

Certain builders have been failing consistently due to regtests timing
out. Attempt to clean-up the tools build dashboard by skipping the
regtests on these builders when -short is set.

Change-Id: Id359eb30cc5e0125e7568b972495a0599c3ccbc8
Reviewed-on: https://go-review.googlesource.com/c/tools/+/276255
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>

Author: findleyr

gopls/internal/regtest/runner.go

@@ -227,10 +227,7 @@ type TestFunc func(t *testing.T, env *Env)
 // un-txtared files specified by filedata.
 func (r *Runner) Run(t *testing.T, files string, test TestFunc, opts ...RunOption) {
 	t.Helper()
-
-	if os.Getenv("GO_BUILDER_NAME") == "openbsd-amd64-64" && testing.Short() {
-		t.Skip("Skipping openbsd-amd64-64 due to golang.org/issues/42789.")
-	}
+	checkBuilder(t)
 
 	tests := []struct {
 		name      string
@@ -320,6 +317,32 @@ func (r *Runner) Run(t *testing.T, files string, test TestFunc, opts ...RunOptio
 	}
 }
 
+// longBuilders maps builders that are skipped when -short is set to a
+// (possibly empty) justification.
+var longBuilders = map[string]string{
+	"openbsd-amd64-64":        "golang.org/issues/42789",
+	"openbsd-386-64":          "golang.org/issues/42789",
+	"openbsd-386-68":          "golang.org/issues/42789",
+	"darwin-amd64-10_12":      "",
+	"freebsd-amd64-race":      "",
+	"illumos-amd64":           "",
+	"netbsd-arm-bsiegert":     "",
+	"solaris-amd64-oraclerel": "",
+	"windows-arm-zx2c4":       "",
+}
+
+func checkBuilder(t *testing.T) {
+	t.Helper()
+	builder := os.Getenv("GO_BUILDER_NAME")
+	if reason, ok := longBuilders[builder]; ok && testing.Short() {
+		if reason != "" {
+			t.Skipf("Skipping %s with -short due to %s", builder, reason)
+		} else {
+			t.Skipf("Skipping %s with -short", builder)
+		}
+	}
+}
+
 type loggingFramer struct {
 	mu  sync.Mutex
 	buf *safeBuffer