Upgrade to current NetBSD popen/pclose.

This gets us back to using vfork now our ARM vfork assembler stub is
fixed, and adds the missing thread safety for the 'pidlist'.

Bug: 5335385
Change-Id: Ib08bfa65b2cb9fa695717aae629ea14816bf988d

libc/upstream-netbsd/env.h

@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _BIONIC_NETBSD_ENV_H_included
+#define _BIONIC_NETBSD_ENV_H_included
+
+/* Placeholder. */
+
+#endif