[gtkmm/sigc3: 1/2] Use C++14

[Murray Cumming <murrayc src gnome org>]

commit 0862607ab9a3fff1aface22828fe95b8399a365e
Author: Murray Cumming <murrayc murrayc com>
Date:   Tue Mar 8 12:46:58 2016 +0100

    Use C++14

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 729228d..687d248 100644
--- a/configure.ac
+++ b/configure.ac
@@ -43,7 +43,7 @@ MM_CONFIG_DOCTOOL_DIR([docs])
 AC_SUBST([LIBGTKMM_SO_VERSION], [2:0:1])
 
 AC_PROG_CXX
-MM_AX_CXX_COMPILE_STDCXX([11], [noext],[mandatory])
+MM_AX_CXX_COMPILE_STDCXX([14], [noext],[mandatory])
 
 AC_DISABLE_STATIC
 LT_INIT([win32-dll])