[glib] gdbusconnection: Fix error in g_dbus_connection_emit_signal() docs

[Philip Withnall <pwithnall src gnome org>]

commit 0664b61782834d3aba501d16441bd8a71a9ab704
Author: Philip Withnall <withnall endlessm com>
Date:   Thu Feb 15 16:42:26 2018 +0000

    gdbusconnection: Fix error in g_dbus_connection_emit_signal() docs
    
    It incorrectly said that an error could only be returned if the GVariant
    was incorrect for the D-Bus API, but that’s not true: an error will also
    be returned if you call it on a closed GDBusConnection.
    
    Clarify that, and mention the actual error codes which are returned.
    
    Signed-off-by: Philip Withnall <withnall endlessm com>
    Reviewed-by: nobody

 gio/gdbusconnection.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/gio/gdbusconnection.c b/gio/gdbusconnection.c
index 6f922c4b2..6f7e5fefc 100644
--- a/gio/gdbusconnection.c
+++ b/gio/gdbusconnection.c
@@ -5516,7 +5516,9 @@ g_dbus_connection_register_object_with_closures (GDBusConnection     *connection
  *
  * If the parameters GVariant is floating, it is consumed.
  *
- * This can only fail if @parameters is not compatible with the D-Bus protocol.
+ * This can only fail if @parameters is not compatible with the D-Bus protocol
+ * (%G_IO_ERROR_INVALID_ARGUMENT), or if @connection has been closed
+ * (%G_IO_ERROR_CLOSED).
  *
  * Returns: %TRUE unless @error is set
  *