mpm_fdqueue: follow up to r1821624.
The code is not part of the API.
#include <apr.h>
-/* Not worth thinking about w/o threads... */
+/* This code is not AP_DECLARE()ed/exported, and use by MPMs event/worker
+ * only (for now), not worth thinking about w/o threads either...
+ */
#if APR_HAS_THREADS
#include "ap_mpm.h"
