Update from Gnulib

Make the following changes by hand, and run 'admin/merge-gnulib'.
* .gitignore: Add lib/malloc/*.gl.h.
* admin/merge-gnulib: Copy lib/af_alg.h and lib/save-cwd.h
directly from Gnulib, without worrying about Gnulib modules,
as these files are special cases.
(AVOIDED_MODULES): Remove malloc-posix.
* lib/malloc.c, lib/realloc.c, m4/malloc.m4, m4/realloc.m4:
* m4/year2038.m4: New files, copied from Gnulib.
* lib/malloca.c, lib/malloca.h:
* m4/close-stream.m4, m4/glibc21.m4, m4/malloca.m4:
Remove.  These are either no longer present in Gnulib, or are no
longer needed by modules that Emacs uses.
* oldXMenu/AddPane.c, oldXmenu/Addsel.c: Include XmenuInt.h first;
needed for new Gnulib.
* src/xmenu.c: Call emacs_abort, not abort.

lib/malloc/dynarray_finalize.c

@@ -3,19 +3,23 @@
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU General Public
+   modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
-   version 3 of the License, or (at your option) any later version.
+   version 2.1 of the License, or (at your option) any later version.
 
    The GNU C Library 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.
+   Lesser General Public License for more details.
 
-   You should have received a copy of the GNU General Public
+   You should have received a copy of the GNU Lesser General Public
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+#ifndef _LIBC
+# include <libc-config.h>
+#endif
+
 #include <dynarray.h>
 #include <stdlib.h>
 #include <string.h>