[gupnp] Clarify _remove_notify usage

[Jens Georg <jensgeorg src gnome org>]

commit a32677a514b33a672db1525e39e49ed595f0d8f4
Author: Jens Georg <mail jensge org>
Date:   Fri Jan 11 16:10:30 2013 +0100

    Clarify _remove_notify usage
    
    Make clear it mustn't be called from a callback, otherwise it will crash since
    it's manipulating the list while iterating over it.

 libgupnp/gupnp-service-proxy.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/libgupnp/gupnp-service-proxy.c b/libgupnp/gupnp-service-proxy.c
index 4aef8d2..c23020d 100644
--- a/libgupnp/gupnp-service-proxy.c
+++ b/libgupnp/gupnp-service-proxy.c
@@ -1524,6 +1524,10 @@ gupnp_service_proxy_add_notify (GUPnPServiceProxy              *proxy,
  *
  * Cancels the variable change notification for @callback and @user_data.
  *
+ * This function must not be called directly or indirectly from a
+ * #GUPnPServiceProxyNotifyCallback associated with this service proxy, even
+ * if it is for another variable.
+ *
  * Return value: %TRUE on success.
  **/
 gboolean