net/internal/socktest: build sys_unix.go on AIX

    
    Reviewed-on: https://go-review.googlesource.com/59913

From-SVN: r251440

gcc/go/gofrontend/MERGE

-930304ec98bfe8e9cccb34d340873958e14255df
+5674b5927d5336e20fbec455a9f7b0b8ed70166c
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/go/net/internal/socktest/sys_unix.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 nacl netbsd openbsd solaris
+// +build aix darwin dragonfly freebsd linux nacl netbsd openbsd solaris
 
 package socktest