[cluttermm/cluttermm-1-18] Use and require C++11.

[Murray Cumming <murrayc src gnome org>]

commit fc3b06e665ede5508fcc6ad1f7a342d7b9082492
Author: Murray Cumming <murrayc murrayc com>
Date:   Wed Sep 16 13:51:27 2015 +0200

    Use and require C++11.

 configure.ac |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 1afab38..aa8f0db 100644
--- a/configure.ac
+++ b/configure.ac
@@ -30,7 +30,7 @@ m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES])
 AM_MAINTAINER_MODE
 AC_ARG_VAR([ACLOCAL_FLAGS], [aclocal flags, e.g. -I <macro dir>])
 
-MM_PREREQ([0.8])
+MM_PREREQ([0.9.8])
 MM_INIT_MODULE([cluttermm-1.0])
 
 # Copy the mm-common .pl scripts into docs/,
@@ -42,6 +42,8 @@ MM_CONFIG_DOCTOOL_DIR([doc])
 AC_SUBST([CLUTTERMM_SO_VERSION], [1:0:0])
 
 AC_PROG_CXX
+MM_AX_CXX_COMPILE_STDCXX_11([noext],[mandatory])
+
 AC_DISABLE_STATIC
 AC_LIBTOOL_WIN32_DLL
 AC_PROG_LIBTOOL