net: skip splice unix-to-tcp tests on android

The android builders are failing on the AF_UNIX part of the new splice
test from CL 113997. Skip them.

Change-Id: Ia0519aae922acb11d2845aa687633935bcd4b1b0
Reviewed-on: https://go-review.googlesource.com/133515
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/net/splice_test.go

@@ -19,6 +19,9 @@ import (
 
 func TestSplice(t *testing.T) {
 	t.Run("tcp-to-tcp", func(t *testing.T) { testSplice(t, "tcp", "tcp") })
+	if !testableNetwork("unixgram") {
+		t.Skip("skipping unix-to-tcp tests")
+	}
 	t.Run("unix-to-tcp", func(t *testing.T) { testSplice(t, "unix", "tcp") })
 }