Certificate trigger and directory operations

Implement trigger of certificate and permission expiries using the timed callbacks.

Implement directory operations such that trusted CA can be read.
This implements OS abstraction functions such as opendir and stat.

Signed-off-by: Stefan Kimmer <skimmer@s2e-systems.com>

src/security/core/include/dds/security/core/dds_security_timed_cb.h

@@ -25,7 +25,11 @@ extern "C" {
  */
 struct dds_security_timed_dispatcher_t;
 
-struct dds_security_timed_cb_data_t;
+/**
+ * The timed callback structure holds a list of dispatchers and manages
+ * the thread that calls the dispatchers callbacks.
+ */
+struct dds_security_timed_cb_data;
 
 /**
  * The callback is triggered by two causes:

src/security/core/src/dds_security_utils.c

@@ -1291,3 +1291,4 @@ DDS_Security_parse_xml_date(
 
   return DDS_TIME_INVALID;
 }
+