[gnote] Bump C++ standard to C++14

[Aurimas Černius <aurimasc src gnome org>]

commit 6bd097d39c3433fad35005b7c6c83f00ff343cde
Author: Aurimas Černius <aurisc4 gmail com>
Date:   Mon Dec 23 18:03:13 2019 +0200

    Bump C++ standard to C++14

 configure.ac                                            |  2 +-
 ...compile_stdcxx_11.m4 => ax_cxx_compile_stdcxx_14.m4} | 17 ++++++-----------
 2 files changed, 7 insertions(+), 12 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 77dd7f83..7f5215b5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -60,7 +60,7 @@ LT_INIT([disable-static])
 
 AC_LANG_CPLUSPLUS
 AC_LANG_COMPILER_REQUIRE
-AX_CXX_COMPILE_STDCXX_11([], [mandatory])
+AX_CXX_COMPILE_STDCXX_14([], [mandatory])
 
 AC_CHECK_PROG(HAVE_DESKTOP_FILE_VALIDATE, [desktop-file-validate], [yes], [no])
 if test $HAVE_DESKTOP_FILE_VALIDATE == "no"; then
diff --git a/m4/ax_cxx_compile_stdcxx_11.m4 b/m4/ax_cxx_compile_stdcxx_14.m4
similarity index 67%
rename from m4/ax_cxx_compile_stdcxx_11.m4
rename to m4/ax_cxx_compile_stdcxx_14.m4
index 1733fd85..094db0d0 100644
--- a/m4/ax_cxx_compile_stdcxx_11.m4
+++ b/m4/ax_cxx_compile_stdcxx_14.m4
@@ -1,19 +1,19 @@
 # =============================================================================
-#  https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx_11.html
+#  https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx_14.html
 # =============================================================================
 #
 # SYNOPSIS
 #
-#   AX_CXX_COMPILE_STDCXX_11([ext|noext], [mandatory|optional])
+#   AX_CXX_COMPILE_STDCXX_14([ext|noext], [mandatory|optional])
 #
 # DESCRIPTION
 #
-#   Check for baseline language coverage in the compiler for the C++11
+#   Check for baseline language coverage in the compiler for the C++14
 #   standard; if necessary, add switches to CXX and CXXCPP to enable
 #   support.
 #
 #   This macro is a convenience alias for calling the AX_CXX_COMPILE_STDCXX
-#   macro with the version set to C++11.  The two optional arguments are
+#   macro with the version set to C++14.  The two optional arguments are
 #   forwarded literally as the second and third argument respectively.
 #   Please see the documentation for the AX_CXX_COMPILE_STDCXX macro for
 #   more information.  If you want to use this macro, you also need to
@@ -21,11 +21,6 @@
 #
 # LICENSE
 #
-#   Copyright (c) 2008 Benjamin Kosnik <bkoz redhat com>
-#   Copyright (c) 2012 Zack Weinberg <zackw panix com>
-#   Copyright (c) 2013 Roy Stogner <roystgnr ices utexas edu>
-#   Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov google com>
-#   Copyright (c) 2015 Paul Norman <penorman mac com>
 #   Copyright (c) 2015 Moritz Klammler <moritz klammler eu>
 #
 #   Copying and distribution of this file, with or without modification, are
@@ -33,7 +28,7 @@
 #   and this notice are preserved. This file is offered as-is, without any
 #   warranty.
 
-#serial 18
+#serial 5
 
 AX_REQUIRE_DEFINED([AX_CXX_COMPILE_STDCXX])
-AC_DEFUN([AX_CXX_COMPILE_STDCXX_11], [AX_CXX_COMPILE_STDCXX([11], [$1], [$2])])
+AC_DEFUN([AX_CXX_COMPILE_STDCXX_14], [AX_CXX_COMPILE_STDCXX([14], [$1], [$2])])