syscall: add aix to syscall_unix_test.go

This file was forgotten during the port of aix/ppc64. In order to make
its tests passed, a few things were added:
- Add termios.h to zerrors
- Add AF_LOCAL = AF_UNIX as this constant doesn't exits natively on AIX
- Fix the alignment in cmsghdr structure.

TestPassFD doesn't work on AIX TL<2 because getsockname isn't working as
expected with unix socket.

Change-Id: I928705bfc78ada29e66df61fe97d8f379f8c739b
Reviewed-on: https://go-review.googlesource.com/c/go/+/171339
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/syscall/syscall_unix_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux netbsd openbsd solaris
+// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris
 
 package syscall_test
 
@@ -17,6 +17,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"strconv"
 	"syscall"
 	"testing"
 	"time"
@@ -131,6 +132,26 @@ func TestFcntlFlock(t *testing.T) {
 func TestPassFD(t *testing.T) {
 	testenv.MustHaveExec(t)
 
+	if runtime.GOOS == "aix" {
+		// Unix network isn't properly working on AIX 7.2 with Technical Level < 2
+		out, err := exec.Command("oslevel", "-s").Output()
+		if err != nil {
+			t.Skipf("skipping on AIX because oslevel -s failed: %v", err)
+		}
+		if len(out) < len("7200-XX-ZZ-YYMM") { // AIX 7.2, Tech Level XX, Service Pack ZZ, date YYMM
+			t.Skip("skipping on AIX because oslevel -s hasn't the right length")
+		}
+		aixVer := string(out[:4])
+		tl, err := strconv.Atoi(string(out[5:7]))
+		if err != nil {
+			t.Skipf("skipping on AIX because oslevel -s output cannot be parsed: %v", err)
+		}
+		if aixVer < "7200" || (aixVer == "7200" && tl < 2) {
+			t.Skip("skipped on AIX versions previous to 7.2 TL 2")
+		}
+
+	}
+
 	if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" {
 		passFDChild()
 		return