drop the os_ prefix on the file names in os. os_test.go can stay.

R=rsc
DELTA=793  (392 added, 392 deleted, 9 changed)
OCL=24777
CL=24804

src/lib/os/env.go

@@ -0,0 +1,27 @@
+// Copyright 2009 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.
+
+// Environment variables.
+// Setenv doesn't exist yet: don't have the run-time hooks yet
+
+package os
+
+import os "os"
+
+var (
+	ENOENV = NewError("no such environment variable");
+)
+
+func Getenv(s string) (v string, err *Error) {
+	n := len(s);
+	if n == 0 {
+		return "", EINVAL
+	}
+	for i, e := range sys.Envs {
+		if len(e) > n && e[n] == '=' && e[0:n] == s {
+			return e[n+1:len(e)], nil
+		}
+	}
+	return "", ENOENV
+}