gdbus-codegen: Strip @since parameters before comparison
gdbus-codegen: Strip @since parameters before comparison

People might put more extraneous whitespace in a @since line in a
documentation comment, which should not affect the ordering of
methods/signals/etc. in the generated output.

https://bugzilla.gnome.org/show_bug.cgi?id=770372

johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib,johne53/MB3Glib,johne53/MB3Glib