[glibmm] Use libsigc++-3.0 and C++14

[Murray Cumming <murrayc src gnome org>]

commit d96310532f8244f89213a78db459d542f95686a7
Author: Murray Cumming <murrayc murrayc com>
Date:   Tue Mar 1 22:50:18 2016 +0100

    Use libsigc++-3.0 and C++14

 configure.ac |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 5e06253..d30f67f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -43,7 +43,7 @@ MM_CONFIG_DOCTOOL_DIR([docs])
 AC_SUBST([LIBGLIBMM_SO_VERSION], [4:0:3])
 
 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])
@@ -64,7 +64,7 @@ AS_IF([test "x$enable_static" = xyes],
 
 glibreq='2.0 >= 2.50.0'
 
-GLIBMM_MODULES="sigc++-2.0 >= 2.9.1 glib-$glibreq gobject-$glibreq gmodule-$glibreq"
+GLIBMM_MODULES="sigc++-3.0 >= 2.99.5 glib-$glibreq gobject-$glibreq gmodule-$glibreq"
 GIOMM_MODULES="$GLIBMM_MODULES gio-$glibreq"
 test "x$glibmm_host_windows" = xyes || GIOMM_MODULES="$GIOMM_MODULES gio-unix-$glibreq"