Import GInitable, GSocket and dependencies from gnio

This adds:
GInitable - failable object constructor interface
GAsyncInitable - async failable object constructor interface
GSocket - Platform independent lowlevel berkely socket style object
GSocketControlMessage - For passing control messages over GSocket
GUnixFDMessage - unix fd passing socket control message

Some changes were done during the import from gnio to make things
work in glib. For instance, types were moved to other headers, header
file boiler plate were updated to glib style and gio.symbols stuff
was added.

gio/giotypes.h

@@ -34,6 +34,7 @@ G_BEGIN_DECLS
 typedef struct _GAppLaunchContext             GAppLaunchContext;
 typedef struct _GAppInfo                      GAppInfo; /* Dummy typedef */
 typedef struct _GAsyncResult                  GAsyncResult; /* Dummy typedef */
+typedef struct _GAsyncInitable                GAsyncInitable;
 typedef struct _GBufferedInputStream          GBufferedInputStream;
 typedef struct _GBufferedOutputStream         GBufferedOutputStream;
 typedef struct _GCancellable                  GCancellable;
@@ -79,6 +80,7 @@ typedef struct _GIcon                         GIcon; /* Dummy typedef */
 typedef struct _GInetAddress                  GInetAddress;
 typedef struct _GInetSocketAddress            GInetSocketAddress;
 typedef struct _GInputStream                  GInputStream;
+typedef struct _GInitable                     GInitable;
 typedef struct _GIOModule                     GIOModule;
 typedef struct _GIOExtensionPoint             GIOExtensionPoint;
 typedef struct _GIOExtension                  GIOExtension;
@@ -107,6 +109,23 @@ typedef struct _GIOStream                     GIOStream;
 typedef struct _GResolver                     GResolver;
 typedef struct _GSeekable                     GSeekable;
 typedef struct _GSimpleAsyncResult            GSimpleAsyncResult;
+
+/**
+ * GSocket:
+ *
+ * A lowlevel network socket object.
+ *
+ * Since: 2.22
+ **/
+typedef struct _GSocket                       GSocket;
+
+/**
+ * GSocketControlMessage:
+ *
+ * Base class for socket-type specific control messages that can be sent and
+ * received over #GSocket.
+ **/
+typedef struct _GSocketControlMessage         GSocketControlMessage;
 typedef struct _GSocketAddress                GSocketAddress;
 typedef struct _GSocketAddressEnumerator      GSocketAddressEnumerator;
 typedef struct _GSocketConnectable            GSocketConnectable;
@@ -202,6 +221,46 @@ typedef void (*GSimpleAsyncThreadFunc) (GSimpleAsyncResult *res,
                                         GObject *object,
                                         GCancellable *cancellable);
 
+/**
+ * GSocketSourceFunc:
+ * @user_data: data passed in by the user.
+ * @condition: the current condition at the source fired.
+ *
+ * This is the function type of the callback used for the #GSource
+ * returned by g_socket_create_source().
+ *
+ * Since: 2.22
+ */
+typedef gboolean (*GSocketSourceFunc) (gpointer user_data,
+				       GIOCondition condition);
+
+/**
+ * GInputVector:
+ *
+ * Structure used for scatter/gather data input.
+ *
+ * Since: 2.22
+ */
+typedef struct
+{
+  gpointer buffer;
+  gsize size;
+} GInputVector;
+
+/**
+ * GOutputVector:
+ *
+ * Structure used for scatter/gather data output.
+ *
+ * Since: 2.22
+ */
+typedef struct
+{
+  gconstpointer buffer;
+  gsize size;
+} GOutputVector;
+
+
 G_END_DECLS
 
 #endif /* __GIO_TYPES_H__ */