ipv6: skip known-failing tests on openbsd-{arm,arm64,mips64}-jsing builders

The arm64 and mips64 builder run OpenBSD 6.8:

OpenBSD gopher-arm64.sing.id.au 6.8 GENERIC.MP#2 arm64

OS: OpenBSD er4.sing.id.au 6.8 GENERIC.MP#0 octeon

The openbsd-arm-jsing builder was offline but according to
it's running at least OpenBSD 6.7. Assuming that this version is
affected as well (or the builder was upgraded to 6.8 in the meantime),
skip TestPacketConnReadWriteMulticastUDP on this builder as well.

For golang/go#11811.
Updates golang/go#42064.

Change-Id: Ia9919057bfc2a69b8884228508ae919ce9d624e9
Reviewed-on: https://go-review.googlesource.com/c/net/+/283752
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Joel Sing <joel@sing.id.au>
diff --git a/ipv6/multicast_test.go b/ipv6/multicast_test.go
index fb127c9..95920f1 100644
--- a/ipv6/multicast_test.go
+++ b/ipv6/multicast_test.go
@@ -28,8 +28,8 @@
 func TestPacketConnReadWriteMulticastUDP(t *testing.T) {
-	if os.Getenv("GO_BUILDER_NAME") == "openbsd-amd64-68" ||
-		os.Getenv("GO_BUILDER_NAME") == "openbsd-386-68" {
+	switch os.Getenv("GO_BUILDER_NAME") {
+	case "openbsd-amd64-68", "openbsd-386-68", "openbsd-arm-jsing", "openbsd-arm64-jsing", "openbsd-mips64-jsing":
 		t.Skip(`this test is currently failing on OpenBSD 6.8 builders with "raw-read udp6: i/o timeout" ` +
 			`and needs investigation, see golang.org/issue/42064`)