Make some APIs that return struct introspectable

In order to do this, we need to define some boxed types. So we need
to add a new dependency, GObject, to GTop.

https://bugzilla.gnome.org/show_bug.cgi?id=663265

include/glibtop/procopenfiles.h

@@ -94,6 +94,42 @@ struct _glibtop_proc_open_files
 	guint64 size;			/* GLIBTOP_PROC_OPEN_FILES_SIZE   */
 };
 
+/**
+ * glibtop_get_proc_open_files:
+ * @server:
+ * @buf: (out):
+ * @all_fs:
+ *
+ * Returns: (transfer none):
+ */
+
+/**
+ * glibtop_get_proc_open_files_l:
+ * @server:
+ * @buf: (out):
+ * @all_fs:
+ *
+ * Returns: (transfer none):
+ */
+
+/**
+ * glibtop_get_proc_open_files_p:
+ * @server:
+ * @buf: (out):
+ * @all_fs:
+ *
+ * Returns: (transfer none):
+ */
+
+/**
+ * glibtop_get_proc_open_files_l:
+ * @server:
+ * @buf: (out):
+ * @all_fs:
+ *
+ * Returns: (transfer none):
+ */
+
 glibtop_open_files_entry *
 glibtop_get_proc_open_files(glibtop_proc_open_files *buf, pid_t pid);
 
@@ -118,6 +154,9 @@ glibtop_open_files_entry *
 glibtop_get_proc_open_files_s (glibtop *server, glibtop_proc_open_files *buf, pid_t pid);
 #endif
 
+GType     glibtop_open_files_entry_get_type (void) G_GNUC_CONST;
+GType     glibtop_proc_open_files_get_type (void) G_GNUC_CONST;
+
 G_END_DECLS
 
 #endif