cmd/dist: skip plugin tests on noopt builder for now

Updates #17937

Change-Id: Ic822da1786a983b3b7bca21b68c3d5fc4bdfaee2
Reviewed-on: https://go-review.googlesource.com/33428
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

src/cmd/dist/test.go

@@ -746,6 +746,14 @@ func (t *tester) supportedBuildmode(mode string) bool {
 		}
 		return false
 	case "plugin":
+		if os.Getenv("GO_BUILDER_NAME") == "linux-amd64-noopt" {
+			// Skip the plugin tests on noopt. They're
+			// causing build failures potentially
+			// obscuring other issues. This is hopefully a
+			// temporary workaround. See golang.org/issue/17937.
+			return false
+		}
+
 		// linux-arm64 is missing because it causes the external linker
 		// to crash, see https://golang.org/issue/17138
 		switch pair {