x/net/ipv4: TestPacketConnReadWriteMulticastICMP failures with `destination unreachable`

[gopherbot]

#!watchflakes
post <- pkg == "golang.org/x/net/ipv4" && test == "TestPacketConnReadWriteMulticastICMP" && `got type=destination unreachable`

Issue created automatically to collect these failures.

Example (log):

--- FAIL: TestPacketConnReadWriteMulticastICMP (2.19s)
    --- FAIL: TestPacketConnReadWriteMulticastICMP/grp=224.0.0.254/src=<nil> (0.00s)
        multicast_test.go:247: got type=destination unreachable, code=3; want type=echo reply, code=0

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
post <- pkg == "golang.org/x/net/ipv4" && test == "TestPacketConnReadWriteMulticastICMP"

2023-03-09 22:21 aix-ppc64 net@9f24bb44 go@b37c0602 x/net/ipv4.TestPacketConnReadWriteMulticastICMP (log)

--- FAIL: TestPacketConnReadWriteMulticastICMP (2.19s)
    --- FAIL: TestPacketConnReadWriteMulticastICMP/grp=224.0.0.254/src=<nil> (0.00s)
        multicast_test.go:247: got type=destination unreachable, code=3; want type=echo reply, code=0

— watchflakes

[bcmills]

(attn @golang/aix)