GUACAMOLE-623: Add configure test for LWS_CALLBACK_CLIENT_CLOSED (only defined in recent libwebsockets and required if present).

configure.ac

@@ -1193,6 +1193,16 @@ then
                  [have_libwebsockets=no])
 fi
 
+# Check for client-specific closed event, which must be used in favor of the
+# generic closed event if libwebsockets is recent enough to provide this
+if test "x$with_websockets" != "xno"
+then
+    AC_CHECK_DECL([LWS_CALLBACK_CLIENT_CLOSED],
+        [AC_DEFINE([HAVE_LWS_CALLBACK_CLIENT_CLOSED],,
+                   [Whether LWS_CALLBACK_CLIENT_CLOSED is defined])],,
+        [#include <libwebsockets.h>])
+fi
+
 AM_CONDITIONAL([ENABLE_WEBSOCKETS],
                [test "x${have_libwebsockets}"  = "xyes"])
 

src/protocols/kubernetes/kubernetes.c

@@ -268,7 +268,6 @@ static int guac_kubernetes_lws_callback(struct lws* wsi,
                 lws_callback_on_writable(wsi);
             break;
 
-        /* TODO: Add configure test */
 #ifdef HAVE_LWS_CALLBACK_CLIENT_CLOSED
         /* Connection closed (client-specific) */
         case LWS_CALLBACK_CLIENT_CLOSED: