Add stuff from gnulib.

gl/setenv.h

@@ -0,0 +1,54 @@
+/* Setting environment variables.
+   Copyright (C) 2001-2004 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#if HAVE_SETENV || HAVE_UNSETENV
+
+/* Get setenv(), unsetenv() declarations.  */
+# include <stdlib.h>
+
+#endif
+
+#ifdef	__cplusplus
+extern "C" {
+#endif
+
+#if !HAVE_SETENV
+
+/* Set NAME to VALUE in the environment.
+   If REPLACE is nonzero, overwrite an existing value.  */
+extern int setenv (const char *name, const char *value, int replace);
+
+#endif
+
+#if HAVE_UNSETENV
+
+# if VOID_UNSETENV
+/* On some systems, unsetenv() returns void.
+   This is the case for FreeBSD 4.8, NetBSD 1.6, OpenBSD 3.4.  */
+#  define unsetenv(name) ((unsetenv)(name), 0)
+# endif
+
+#else
+
+/* Remove the variable NAME from the environment.  */
+extern int unsetenv (const char *name);
+
+#endif
+
+#ifdef	__cplusplus
+}
+#endif