mkheader puts a space in the wrong place in some cases

From IRC:

<mwichmann> one oddity is for function pointer members, if the "return type" is
from the gtk stack, the space goes before, not after....
 this is "not me", as far as I can tell
 examples:
 as expected:
 + void (*move_focus_out) (GtkNotebook * notebook,
 + GtkDirectionType direction);
 not quite as expected:
 + gboolean(*change_current_page) (GtkNotebook * notebook,
 + gint offset);

This was discovered when fixing up GTK+ 3, but has also been discovered in
older headers, such as GTK+ 2.