net: allow build on aix/ppc64 with cgo

This commit adds C support for net package for aix/ppc64.

Change-Id: I704710991fc013c6ec3511671def6791df4854f1
Reviewed-on: https://go-review.googlesource.com/c/go/+/164038
Run-TryBot: Mikio Hara <mikioh.public.networking@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Mikio Hara <mikioh.public.networking@gmail.com>

src/net/cgo_aix.go

+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build cgo,!netgo
+
+package net
+
+/*
+#include <sys/types.h>
+#include <sys/socket.h>
+
+#include <netdb.h>
+*/
+import "C"
+
+import "unsafe"
+
+const cgoAddrInfoFlags = C.AI_CANONNAME
+
+func cgoNameinfoPTR(b []byte, sa *C.struct_sockaddr, salen C.socklen_t) (int, error) {
+	gerrno, err := C.getnameinfo(sa, C.size_t(salen), (*C.char)(unsafe.Pointer(&b[0])), C.size_t(len(b)), nil, 0, C.NI_NAMEREQD)
+	return int(gerrno), err
+}

src/net/cgo_sockold.go

@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // +build cgo,!netgo
-// +build darwin dragonfly freebsd netbsd openbsd
+// +build aix darwin dragonfly freebsd netbsd openbsd
 
 package net
 

src/net/cgo_unix.go

@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // +build cgo,!netgo
-// +build darwin dragonfly freebsd linux netbsd openbsd solaris
+// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris
 
 package net
 
@@ -14,6 +14,11 @@ package net
 #include <netdb.h>
 #include <unistd.h>
 #include <string.h>
+
+// If nothing else defined EAI_OVERFLOW, make sure it has a value.
+#ifndef EAI_OVERFLOW
+#define EAI_OVERFLOW -12
+#endif
 */
 import "C"
 

src/net/cgo_unix_test.go

@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // +build cgo,!netgo
-// +build darwin dragonfly freebsd linux netbsd openbsd solaris
+// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris
 
 package net