Fix compilation with glibc-2.16.
https://bugs.gentoo.org/424755

Patch backported from gnulib upstream:

From 66712c23388e93e5c518ebc8515140fa0c807348 Mon Sep 17 00:00:00 2001
From: Eric Blake <eblake@redhat.com>
Date: Thu, 29 Mar 2012 13:30:41 -0600
Subject: [PATCH 1/1] stdio: don't assume gets any more

Gnulib intentionally does not have a gets module, and now that C11
and glibc have dropped it, we should be more proactive about warning
any user on a platform that still has a declaration of this dangerous
interface.

--- emacs-24.1-orig/lib/gnulib.mk
+++ emacs-24.1/lib/gnulib.mk
@@ -599,7 +624,6 @@
 	      -e 's/@''GNULIB_GETCHAR''@/$(GNULIB_GETCHAR)/g' \
 	      -e 's/@''GNULIB_GETDELIM''@/$(GNULIB_GETDELIM)/g' \
 	      -e 's/@''GNULIB_GETLINE''@/$(GNULIB_GETLINE)/g' \
-	      -e 's/@''GNULIB_GETS''@/$(GNULIB_GETS)/g' \
 	      -e 's/@''GNULIB_OBSTACK_PRINTF''@/$(GNULIB_OBSTACK_PRINTF)/g' \
 	      -e 's/@''GNULIB_OBSTACK_PRINTF_POSIX''@/$(GNULIB_OBSTACK_PRINTF_POSIX)/g' \
 	      -e 's/@''GNULIB_PCLOSE''@/$(GNULIB_PCLOSE)/g' \
--- emacs-24.1-orig/lib/stdio.in.h
+++ emacs-24.1/lib/stdio.in.h
@@ -699,22 +699,11 @@
 # endif
 #endif
 
-#if @GNULIB_GETS@
-# if @REPLACE_STDIO_READ_FUNCS@ && @GNULIB_STDIO_H_NONBLOCKING@
-#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
-#   undef gets
-#   define gets rpl_gets
-#  endif
-_GL_FUNCDECL_RPL (gets, char *, (char *s) _GL_ARG_NONNULL ((1)));
-_GL_CXXALIAS_RPL (gets, char *, (char *s));
-# else
-_GL_CXXALIAS_SYS (gets, char *, (char *s));
-#  undef gets
-# endif
-_GL_CXXALIASWARN (gets);
 /* It is very rare that the developer ever has full control of stdin,
-   so any use of gets warrants an unconditional warning.  Assume it is
-   always declared, since it is required by C89.  */
+   so any use of gets warrants an unconditional warning; besides, C11
+   removed it.  */
+#undef gets
+#if HAVE_RAW_DECL_GETS
 _GL_WARN_ON_USE (gets, "gets is a security hole - use fgets instead");
 #endif
 
@@ -1054,9 +1043,9 @@
 # endif
 #endif
 
-/* Some people would argue that sprintf should be handled like gets
-   (for example, OpenBSD issues a link warning for both functions),
-   since both can cause security holes due to buffer overruns.
+/* Some people would argue that all sprintf uses should be warned about
+   (for example, OpenBSD issues a link warning for it),
+   since it can cause security holes due to buffer overruns.
    However, we believe that sprintf can be used safely, and is more
    efficient than snprintf in those safe cases; and as proof of our
    belief, we use sprintf in several gnulib modules.  So this header
--- emacs-24.1-orig/m4/stdio_h.m4
+++ emacs-24.1/m4/stdio_h.m4
@@ -1,4 +1,4 @@
-# stdio_h.m4 serial 40
+# stdio_h.m4 serial 41
 dnl Copyright (C) 2007-2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -18,7 +18,6 @@
   GNULIB_GETC=1
   GNULIB_GETCHAR=1
   GNULIB_FGETS=1
-  GNULIB_GETS=1
   GNULIB_FREAD=1
   dnl This ifdef is necessary to avoid an error "missing file lib/stdio-read.c"
   dnl "expected source file, required through AC_LIBSOURCES, not found". It is
@@ -72,10 +71,10 @@
 
   dnl Check for declarations of anything we want to poison if the
   dnl corresponding gnulib module is not in use, and which is not
-  dnl guaranteed by C89.
+  dnl guaranteed by both C89 and C11.
   gl_WARN_ON_USE_PREPARE([[#include <stdio.h>
-    ]], [dprintf fpurge fseeko ftello getdelim getline pclose popen renameat
-    snprintf tmpfile vdprintf vsnprintf])
+    ]], [dprintf fpurge fseeko ftello getdelim getline gets pclose popen
+    renameat snprintf tmpfile vdprintf vsnprintf])
 ])
 
 AC_DEFUN([gl_STDIO_MODULE_INDICATOR],
@@ -113,7 +112,6 @@
   GNULIB_GETCHAR=0;              AC_SUBST([GNULIB_GETCHAR])
   GNULIB_GETDELIM=0;             AC_SUBST([GNULIB_GETDELIM])
   GNULIB_GETLINE=0;              AC_SUBST([GNULIB_GETLINE])
-  GNULIB_GETS=0;                 AC_SUBST([GNULIB_GETS])
   GNULIB_OBSTACK_PRINTF=0;       AC_SUBST([GNULIB_OBSTACK_PRINTF])
   GNULIB_OBSTACK_PRINTF_POSIX=0; AC_SUBST([GNULIB_OBSTACK_PRINTF_POSIX])
   GNULIB_PCLOSE=0;               AC_SUBST([GNULIB_PCLOSE])