drivers: fix build for aix

Reuse Brad's fix for solaris in CL 170785 for aix.

Change-Id: I4075b2b74fd5cab87c8e072eae4af762118194f0
Reviewed-on: https://go-review.googlesource.com/c/benchmarks/+/170977
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/driver/driver_stub.go b/driver/driver_stub.go
index d964039..31ff843 100644
--- a/driver/driver_stub.go
+++ b/driver/driver_stub.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 dragonfly freebsd netbsd openbsd solaris
+//+build aix dragonfly freebsd netbsd openbsd solaris
 
 package driver
 
diff --git a/driver/driver_unix.go b/driver/driver_unix.go
index 76c5463..2a35e7b 100644
--- a/driver/driver_unix.go
+++ b/driver/driver_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 netbsd openbsd solaris
+// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris
 
 package driver