GUACAMOLE-935: Merge do not assign SVC plugin context as it may be automatically freed.

diff --git a/src/protocols/rdp/plugins/guac-common-svc/guac-common-svc.c b/src/protocols/rdp/plugins/guac-common-svc/guac-common-svc.c
index fbba484..535cb45 100644
--- a/src/protocols/rdp/plugins/guac-common-svc/guac-common-svc.c
+++ b/src/protocols/rdp/plugins/guac-common-svc/guac-common-svc.c
@@ -294,7 +294,7 @@
     svc->_init_handle = init_handle;
 
     /* Complete initialization */
-    if (svc->_entry_points.pVirtualChannelInitEx(svc, svc, init_handle,
+    if (svc->_entry_points.pVirtualChannelInitEx(svc, NULL, init_handle,
                 &svc->_channel_def, 1, VIRTUAL_CHANNEL_VERSION_WIN2000,
                 guac_rdp_common_svc_handle_init_event) != CHANNEL_RC_OK) {
         return FALSE;