jhbuild configuration to follow gtk+ trunk

["Marko Anastasov" <marko anastasov gmail com>]

I'm currently set up to build moduleset 2.22. That pulls gtkmm trunk.
However, gtkmm trunk depends on gtk+ trunk (eg the new calendar stuff)
but gnome 2.22 depends on gtk+ 2.12, which is the branch that is built.

I was going to ask something but while typing the last paragraph
I realized that I could simply modify my local moduleset file to fetch gtk+
trunk. So this can be considered as a helping note which might to somebody
wondering how to fix this.

    Marko