gtkmm does not build on 10.6.1

[hwr@…]

I was trying to build gobby, which failed because gtkmm failed to build on 10.6.1:

--->  Building gtkmm
Error: Target org.macports.build returned: shell command " cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_x11_gtkmm/work/gtkmm-2.16.0" && /usr/bin/make -j2 all " returned error 2
Command output: /usr/bin/make  all-recursive
Making all in src
make[4]: Nothing to be done for `all'.
Making all in gdkmm
Making all in private
make[5]: Nothing to be done for `all'.
make[5]: Nothing to be done for `all-am'.
make[4]: Nothing to be done for `all-am'.
Making all in gtk
/usr/bin/make  all-recursive
Making all in src
make[4]: Nothing to be done for `all'.
Making all in gtkmm
Making all in private
make[5]: Nothing to be done for `all'.
/bin/sh ../../libtool --tag=CXX   --mode=compile /usr/bin/g++-4.2 -DHAVE_CONFIG_H -DG_LOG_DOMAIN=\"gtkmm\"   -I../../gtk -I../../gtk -I../../pango -I../../pango -I../../atk -I../../atk -I../../gdk -I../../gdk -I../../gtk -I../../gtk -I/opt/local/include/glibmm-2.4 -I/opt/local/lib/glibmm-2.4/include -I/opt/local/include/sigc++-2.0 -I/opt/local/lib/sigc++-2.0/include -I/opt/local/include/glib-2.0 -I/opt/local/lib/glib-2.0/include -I/opt/local/include -I/opt/local/include/giomm-2.4 -I/opt/local/lib/giomm-2.4/include -I/opt/local/include/cairomm-1.0 -I/opt/local/include/cairo -I/opt/local/include/pixman-1 -I/opt/local/include/freetype2 -I/opt/local/include/libpng12 -I/opt/local/include/pangomm-1.4 -I/opt/local/include/pango-1.0 -I/opt/local/include/gtk-2.0 -I/opt/local/lib/gtk-2.0/include -I/opt/local/include/atk-1.0 -I/opt/local/include/gtk-unix-print-2.0 -D_REENTRANT -I/opt/local/include/glib-2.0 -I/opt/local/lib/glib-2.0/include -I/opt/local/include    -I/opt/local/include  -O2 -arch i386 -Wall -MT recentinfo.lo -MD -MP -MF .deps/recentinfo.Tpo -c -o recentinfo.lo recentinfo.cc
/bin/sh ../../libtool --tag=CXX   --mode=compile /usr/bin/g++-4.2 -DHAVE_CONFIG_H -DG_LOG_DOMAIN=\"gtkmm\"   -I../../gtk -I../../gtk -I../../pango -I../../pango -I../../atk -I../../atk -I../../gdk -I../../gdk -I../../gtk -I../../gtk -I/opt/local/include/glibmm-2.4 -I/opt/local/lib/glibmm-2.4/include -I/opt/local/include/sigc++-2.0 -I/opt/local/lib/sigc++-2.0/include -I/opt/local/include/glib-2.0 -I/opt/local/lib/glib-2.0/include -I/opt/local/include -I/opt/local/include/giomm-2.4 -I/opt/local/lib/giomm-2.4/include -I/opt/local/include/cairomm-1.0 -I/opt/local/include/cairo -I/opt/local/include/pixman-1 -I/opt/local/include/freetype2 -I/opt/local/include/libpng12 -I/opt/local/include/pangomm-1.4 -I/opt/local/include/pango-1.0 -I/opt/local/include/gtk-2.0 -I/opt/local/lib/gtk-2.0/include -I/opt/local/include/atk-1.0 -I/opt/local/include/gtk-unix-print-2.0 -D_REENTRANT -I/opt/local/include/glib-2.0 -I/opt/local/lib/glib-2.0/include -I/opt/local/include    -I/opt/local/include  -O2 -arch i386 -Wall -MT ruler.lo -MD -MP -MF .deps/ruler.Tpo -c -o ruler.lo ruler.cc
 /usr/bin/g++-4.2 -DHAVE_CONFIG_H -DG_LOG_DOMAIN=\"gtkmm\" -I../../gtk -I../../gtk -I../../pango -I../../pango -I../../atk -I../../atk -I../../gdk -I../../gdk -I../../gtk -I../../gtk -I/opt/local/include/glibmm-2.4 -I/opt/local/lib/glibmm-2.4/include -I/opt/local/include/sigc++-2.0 -I/opt/local/lib/sigc++-2.0/include -I/opt/local/include/glib-2.0 -I/opt/local/lib/glib-2.0/include -I/opt/local/include -I/opt/local/include/giomm-2.4 -I/opt/local/lib/giomm-2.4/include -I/opt/local/include/cairomm-1.0 -I/opt/local/include/cairo -I/opt/local/include/pixman-1 -I/opt/local/include/freetype2 -I/opt/local/include/libpng12 -I/opt/local/include/pangomm-1.4 -I/opt/local/include/pango-1.0 -I/opt/local/include/gtk-2.0 -I/opt/local/lib/gtk-2.0/include -I/opt/local/include/atk-1.0 -I/opt/local/include/gtk-unix-print-2.0 -D_REENTRANT -I/opt/local/include/glib-2.0 -I/opt/local/lib/glib-2.0/include -I/opt/local/include -I/opt/local/include -O2 -arch i386 -Wall -MT recentinfo.lo -MD -MP -MF .deps/recentinfo.Tpo -c recentinfo.cc  -fno-common -DPIC -o .libs/recentinfo.o
 /usr/bin/g++-4.2 -DHAVE_CONFIG_H -DG_LOG_DOMAIN=\"gtkmm\" -I../../gtk -I../../gtk -I../../pango -I../../pango -I../../atk -I../../atk -I../../gdk -I../../gdk -I../../gtk -I../../gtk -I/opt/local/include/glibmm-2.4 -I/opt/local/lib/glibmm-2.4/include -I/opt/local/include/sigc++-2.0 -I/opt/local/lib/sigc++-2.0/include -I/opt/local/include/glib-2.0 -I/opt/local/lib/glib-2.0/include -I/opt/local/include -I/opt/local/include/giomm-2.4 -I/opt/local/lib/giomm-2.4/include -I/opt/local/include/cairomm-1.0 -I/opt/local/include/cairo -I/opt/local/include/pixman-1 -I/opt/local/include/freetype2 -I/opt/local/include/libpng12 -I/opt/local/include/pangomm-1.4 -I/opt/local/include/pango-1.0 -I/opt/local/include/gtk-2.0 -I/opt/local/lib/gtk-2.0/include -I/opt/local/include/atk-1.0 -I/opt/local/include/gtk-unix-print-2.0 -D_REENTRANT -I/opt/local/include/glib-2.0 -I/opt/local/lib/glib-2.0/include -I/opt/local/include -I/opt/local/include -O2 -arch i386 -Wall -MT ruler.lo -MD -MP -MF .deps/ruler.Tpo -c ruler.cc  -fno-common -DPIC -o .libs/ruler.o
recentinfo.cc: In member function 'bool Gtk::RecentInfo::get_application_info(const Glib::ustring&, Glib::StringArrayHandle&, guint&, time_t&) const':
recentinfo.cc:192: error: invalid conversion from 'gchar**' to 'const gchar**'
recentinfo.cc:192: error:   initializing argument 3 of 'gboolean gtk_recent_info_get_application_info(GtkRecentInfo*, const gchar*, const gchar**, guint*, time_t*)'
make[5]: *** [recentinfo.lo] Error 1
make[5]: *** Waiting for unfinished jobs....
mv -f .deps/ruler.Tpo .deps/ruler.Plo
make[4]: *** [all-recursive] Error 1
make[3]: *** [all-recursive] Error 1
make[2]: *** [all] Error 2
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2

Error: The following dependencies failed to build: gtkmm gtksourceview2 libgnomecups libxmlxx2 net6 gnutls libgcrypt libgpg-error libtasn1 lzo opencdk obby avahi dbus dbus-glib dbus-python25 py25-gobject python25 py25-numeric libdaemon libglade2 py25-gtk py25-cairo py25-numpy fftw-3 py25-nose py25-setuptools
Error: Status 1 encountered during processing.