os test: Tidy up build tags

Author: dkegel-fastly

src/os/dir_other.go

@@ -1,4 +1,4 @@
-// +build go1.16,baremetal go1.16,wasi go1.16,arm go1.16,386
+// +build go1.16,baremetal go1.16,arm,!wasi go1.16,386,!wasi
 
 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

src/os/dir_good.go renamed to src/os/dir_seek_good.go

@@ -4,7 +4,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// All the common bits that involve DirEntry, which pulls in seek, which causes build failure on i386 and arm.
+// This file is a kludge.  It contains the common bits that involve DirEntry,
+// which pulls in seek, which causes build failure on i386 and arm.
+// TODO: move these bits back where they belong once Go Assembly is implemented and seek works everywhere.
 
 package os
 

src/os/dir_test.go

@@ -1,4 +1,4 @@
-// +build darwin linux,!baremetal,!wasi
+// +build go1.16,darwin go1.16,linux,!baremetal,!wasi
 
 package os_test