[glibmm] Require the latest libsigc++-2.0.

[Murray Cumming <murrayc src gnome org>]

commit b466cb74e179952f47953cb40467ffaed5aac78f
Author: Murray Cumming <murrayc murrayc com>
Date:   Fri Mar 11 14:36:18 2016 +0100

    Require the latest libsigc++-2.0.
    
    In case we really need the std::ref() support in libsigc++ 2.7.2.

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index b7b81b2..c5458f5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -64,7 +64,7 @@ AS_IF([test "x$enable_static" = xyes],
 
 glibreq='2.0 >= 2.47.6'
 
-GLIBMM_MODULES="sigc++-2.0 >= 2.6.0 glib-$glibreq gobject-$glibreq gmodule-$glibreq"
+GLIBMM_MODULES="sigc++-2.0 >= 2.7.2 glib-$glibreq gobject-$glibreq gmodule-$glibreq"
 GIOMM_MODULES="$GLIBMM_MODULES gio-$glibreq"
 test "x$glibmm_host_windows" = xyes || GIOMM_MODULES="$GIOMM_MODULES gio-unix-$glibreq"