[atkmm] Use the glibmm-2.52 API instead of glibmm-2.4 ABI.

[Murray Cumming <murrayc src gnome org>]

commit c76524a1dce4d1fc5a3952b8027fab60e7fec4ae
Author: Murray Cumming <murrayc murrayc com>
Date:   Fri Nov 11 09:56:18 2016 +0100

    Use the glibmm-2.52 API instead of glibmm-2.4 ABI.

 configure.ac |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 3f35175..40534f9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -51,18 +51,18 @@ MM_AX_CXX_COMPILE_STDCXX([11], [noext], [mandatory])
 AC_DISABLE_STATIC
 LT_INIT([win32-dll])
 
-AC_SUBST([ATKMM_MODULES], ['atk >= 1.18 glibmm-2.4 >= 2.46.2'])
+AC_SUBST([ATKMM_MODULES], ['atk >= 1.18 glibmm-2.52 >= 2.46.2'])
 PKG_CHECK_MODULES([ATKMM], [$ATKMM_MODULES])
 
 MM_PKG_CONFIG_SUBST([GTHREAD_CFLAGS], [--cflags-only-other gthread-2.0])
-MM_PKG_CONFIG_SUBST([GMMPROC_DIR], [--variable=gmmprocdir glibmm-2.4])
+MM_PKG_CONFIG_SUBST([GMMPROC_DIR], [--variable=gmmprocdir glibmm-2.52])
 
 MM_ARG_DISABLE_DEPRECATED_API
 
 MM_ARG_ENABLE_DOCUMENTATION
 MM_ARG_WITH_TAGFILE_DOC([libstdc++.tag], [mm-common-libstdc++])
-MM_ARG_WITH_TAGFILE_DOC([libsigc++-2.0.tag], [sigc++-2.0])
-MM_ARG_WITH_TAGFILE_DOC([glibmm-2.4.tag], [glibmm-2.4])
+MM_ARG_WITH_TAGFILE_DOC([libsigc++-3.0.tag], [sigc++-3.0])
+MM_ARG_WITH_TAGFILE_DOC([glibmm-2.52.tag], [glibmm-2.52])
 
 AC_LANG([C++])
 MM_ARG_ENABLE_WARNINGS([ATKMM_WXXFLAGS],