Sync from gnulib

This incorporates:
2016-05-01 mktime: port to stricter signed overflow checking
2016-05-01 mktime: speed up DEBUG_MKTIME benchmarks
2016-05-01 mktime: resurrect DEBUG_MKTIME testing
2016-05-01 mktime: simplify DEBUG_MKTIME
2016-05-01 Port mktime_internal offset to unsigned time_t
2016-04-27 xstrtol: prohibit monstrosities like "1bB"
2016-04-13 mktime: improve integer overflow checking
2016-04-13 intprops: check two's complement assumption
2016-04-13 intprops, mktime, strtol: assume two's complement
* lib/intprops.h, lib/mktime-internal.h, lib/mktime.c:
* lib/strtol.c, lib/timegm.c, m4/mktime.m4, m4/std-gnu11.m4:
Copy from gnulib.

2 files changed, 22 insertions, 8 deletions

diff --git a/m4/mktime.m4 b/m4/mktime.m4
index 78f16ba66a..5a0f2d88ab 100644
--- a/m4/mktime.m4
+++ b/m4/mktime.m4
@@ -1,4 +1,4 @@
-# serial 25
+# serial 26
 dnl Copyright (C) 2002-2003, 2005-2007, 2009-2016 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
@@ -7,9 +7,24 @@ dnl with or without modifications, as long as this notice is preserved.
 
 dnl From Jim Meyering.
 
+AC_DEFUN([gl_TIME_T_IS_SIGNED],
+[
+  AC_CACHE_CHECK([whether time_t is signed],
+    [gl_cv_time_t_is_signed],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM([[#include <time.h>
+                          char time_t_signed[(time_t) -1 < 0 ? 1 : -1];]])],
+       [gl_cv_time_t_is_signed=yes],
+       [gl_cv_time_t_is_signed=no])])
+  if test $gl_cv_time_t_is_signed = yes; then
+    AC_DEFINE([TIME_T_IS_SIGNED], [1], [Define to 1 if time_t is signed.])
+  fi
+])
+
 AC_DEFUN([gl_FUNC_MKTIME],
 [
   AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
+  AC_REQUIRE([gl_TIME_T_IS_SIGNED])
 
   dnl We don't use AC_FUNC_MKTIME any more, because it is no longer maintained
   dnl in Autoconf and because it invokes AC_LIBOBJ.
@@ -169,7 +184,6 @@ main ()
   time_t t, delta;
   int i, j;
   int time_t_signed_magnitude = (time_t) ~ (time_t) 0 < (time_t) -1;
-  int time_t_signed = ! ((time_t) 0 < (time_t) -1);
 
 #if HAVE_DECL_ALARM
   /* This test makes some buggy mktime implementations loop.
@@ -179,11 +193,11 @@ main ()
   alarm (60);
 #endif
 
-  time_t_max = (! time_t_signed
+  time_t_max = (! TIME_T_IS_SIGNED
                 ? (time_t) -1
                 : ((((time_t) 1 << (sizeof (time_t) * CHAR_BIT - 2)) - 1)
                    * 2 + 1));
-  time_t_min = (! time_t_signed
+  time_t_min = (! TIME_T_IS_SIGNED
                 ? (time_t) 0
                 : time_t_signed_magnitude
                 ? ~ (time_t) 0
diff --git a/m4/std-gnu11.m4 b/m4/std-gnu11.m4
index e8d3ebcf2f..10da26f130 100644
--- a/m4/std-gnu11.m4
+++ b/m4/std-gnu11.m4
@@ -1,8 +1,8 @@
 # Prefer GNU C11 and C++11 to earlier versions.  -*- coding: utf-8 -*-
 
 # This implementation is taken from GNU Autoconf lib/autoconf/c.m4
-# commit 739cdc82b5325402231f3f5e1a38f681fcbd1db2
-# dated Tue Mar 15 09:34:11 2016 -0700.
+# commit 017d5ddd82854911f0119691d91ea8a1438824d6
+# dated Sun Apr 3 13:57:17 2016 -0700
 # This implementation will be obsolete once we can assume Autoconf 2.70
 # or later is installed everywhere a Gnulib program might be developed.
 
@@ -707,7 +707,7 @@ AC_DEFUN([_AC_CXX_CXX11_TEST_BODY],
   short sa[cxx11test::get_val()] = { 0 };
 }
 {
-  // Test initialiser lists
+  // Test initializer lists
   cxx11test::testinit il = { 4323, 435234.23544 };
 }
 {
@@ -801,7 +801,7 @@ dnl with extended modes being tried first.
 # considers the compiler to be in ISO C++11 mode if it handles all the
 # tests from the C++98 checks, plus the following: Language features
 # (auto, constexpr, decltype, default/deleted constructors, delegate
-# constructors, final, initialiser lists, lambda functions, nullptr,
+# constructors, final, initializer lists, lambda functions, nullptr,
 # override, range-based for loops, template brackets without spaces,
 # unicode literals) and library features (array, memory (shared_ptr,
 # weak_ptr), regex and tuple types).