gnulib: add the closeout and secure_getenv modules

* lib/close-stream.c, lib/close-stream.h, lib/closeout.c,
lib/closeout.h, lib/fpending.c, lib/fpending.h, lib/stdio-impl.h,
lib/secure_getenv.c, m4/close-stream.m4, m4/closeout.m4,
m4/fpending.m4, m4/secure_getenv.m4: New file.
* lib/Makefile.am, m4/gnulib-cache.m4, m4/gnulib-comp.m4: Update.

lib/fpending.h

@@ -0,0 +1,29 @@
+/* Declare __fpending.
+
+   Copyright (C) 2000, 2003, 2005-2006, 2009-2018 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 3 of the License, 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, see <https://www.gnu.org/licenses/>.
+
+   Written by Jim Meyering.  */
+
+#include <stddef.h>
+#include <stdio.h>
+#if HAVE_STDIO_EXT_H
+# include <stdio_ext.h>
+#endif
+
+#if !HAVE_DECL___FPENDING
+size_t __fpending (FILE *) _GL_ATTRIBUTE_PURE;
+#endif