Add GNativeSocketAddress for handling "other" addresses

Instead of just dropping address types that we're not specifically
handling we return a GNativeSocketAddress which is just a dummy
container for the stuct sockaddr.

https://bugzilla.gnome.org/show_bug.cgi?id=750203

gio/giotypes.h

@@ -103,6 +103,7 @@ typedef struct _GIcon                         GIcon; /* Dummy typedef */
 typedef struct _GInetAddress                  GInetAddress;
 typedef struct _GInetAddressMask              GInetAddressMask;
 typedef struct _GInetSocketAddress            GInetSocketAddress;
+typedef struct _GNativeSocketAddress          GNativeSocketAddress;
 typedef struct _GInputStream                  GInputStream;
 typedef struct _GInitable                     GInitable;
 typedef struct _GIOModule                     GIOModule;