net: fix darwin/amd64 build

Accidental semantics change in 4c6364a8.

Change-Id: I0bbfc441662d79af4dbac6f9fc4e3a485adfb924
Reviewed-on: https://go-review.googlesource.com/6831Reviewed-by: Minux Ma <minux@golang.org>

src/net/server_test.go

@@ -22,8 +22,10 @@ func skipServerTest(net, unixsotype, addr string, ipv6, ipv4map, linuxOnly bool)
 			return true
 		}
 	case "darwin":
-		if runtime.GOARCH == "arm" && net == unixsotype {
-			return true
+		if net == unixsotype {
+			if runtime.GOARCH == "arm" || linuxOnly {
+				return true
+			}
 		}
 	default:
 		if net == unixsotype && linuxOnly {