gtk3: function pointers, enums, structs misdefined

[Jeff Johnson]

Some filter function pointers have incomplete definitions for the LSB
gtk-3.0 import, as shown by the following snips:

Upstream Gtk2:
typedef gboolean (*GtkFileFilterFunc) (const GtkFileFilterInfo *filter_info,
                                       gpointer data);
typedef gboolean (*GtkRecentFilterFunc) (const GtkRecentFilterInfo
*filter_info,
                                         gpointer user_data);
typedef GdkFilterReturn (*GdkFilterFunc) (GdkXEvent *xevent,
                                          GdkEvent *event,
                                          gpointer data);

Upstream Gtk3:
typedef gboolean (*GtkFileFilterFunc) (const GtkFileFilterInfo *filter_info,
                                       gpointer data);
typedef gboolean (*GtkFontFilterFunc) (const PangoFontFamily *family,
                                       const PangoFontFace *face,
                                       gpointer data);
typedef gboolean (*GtkRecentFilterFunc) (const GtkRecentFilterInfo
*filter_info,
                                         gpointer user_data);
typedef GdkFilterReturn (*GdkFilterFunc) (GdkXEvent *xevent,
                                          GdkEvent *event,
                                          gpointer data);

LSB Gtk2:
    typedef gboolean(*GtkFileFilterFunc) (const GtkFileFilterInfo *,
                                          gpointer);
    typedef gboolean(*GtkRecentFilterFunc) (const GtkRecentFilterInfo *,
                                            gpointer);
    typedef GdkFilterReturn(*GdkFilterFunc) (GdkXEvent *, GdkEvent *,
                                             gpointer);

LSB Gtk3:
    typedef gboolean(*GtkFileFilterFunc) (void);
    typedef gboolean(*GtkFontFilterFunc) (void);
    typedef gboolean(*GtkRecentFilterFunc) (void);
    typedef GdkFilterReturn(*GdkFilterFunc) (void);