Properly deal with classes destructors

There are some classes such as AuditLog that demands a reference count. That is
needed because this class can be used by different instances of the Rules
classes.

src/modsecurity.cc

@@ -45,6 +45,10 @@ ModSecurity::ModSecurity()
 }
 
 
+ModSecurity::~ModSecurity() {
+}
+
+
 /**
  * @name    whoAmI
  * @brief   Return information about this ModSecurity version and platform.
@@ -162,6 +166,18 @@ extern "C" const char *msc_who_am_i(ModSecurity *msc) {
 }
 
 
+/**
+ * @name    msc_cleanup
+ * @brief   Cleanup ModSecurity C API
+ *
+ * Cleanup ModSecurity instance.
+ *
+ */
+extern "C" void msc_cleanup(ModSecurity *msc) {
+    delete msc;
+}
+
+
 /**
  * @name    msc_init
  * @brief   Initilizes ModSecurity C API