http2/h2i: add port for aix/ppc64

Change-Id: I46758e5685a0eebbe38b0f228fbc084d9ead35b7
Reviewed-on: https://go-review.googlesource.com/c/net/+/170561
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

http2/h2i/h2i.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 windows
+// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris windows
 
 /*
 The h2i command is an interactive HTTP/2 console.