Fix maintainer-clean
Fix maintainer-clean

gtkimcontextsimpleseqs.h is not really autogenerated but shipped

https://bugzilla.gnome.org/show_bug.cgi?id=630708

Distrotech/gtk,Distrotech/gtk,Unity-Technologies/gtk,Unity-Technologies/gtk,Unity-Technologies/gtk,johne53/MB3Gtk-2,Distrotech/gtk,johne53/MB3Gtk-2,Distrotech/gtk,johne53/MB3Gtk-2,Unity-Technologies/gtk,Unity-Technologies/gtk,johne53/MB3Gtk-2,Distrotech/gtk,johne53/MB3Gtk-2