river-control: mark callback events as destructors

 protocol/river-control-unstable-v1.xml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/protocol/river-control-unstable-v1.xml b/protocol/river-control-unstable-v1.xml
index b8faa45..aa5fc4d 100644
--- a/protocol/river-control-unstable-v1.xml
+++ b/protocol/river-control-unstable-v1.xml
@@ -63,7 +63,7 @@
       by the compositor after one of the events is sent.
     </description>
 
-    <event name="success">
+    <event name="success" type="destructor">
       <description summary="command successful">
         Sent when the command has been successfully received and executed by
         the compositor. Some commands may produce output, in which case the
@@ -72,7 +72,7 @@
       <arg name="output" type="string" summary="the output of the command"/>
     </event>
 
-    <event name="failure">
+    <event name="failure" type="destructor">
       <description summary="command failed">
         Sent when the command could not be carried out. This could be due to
         sending a non-existent command, no command, not enough arguments, too