Allow getting background queue out of kafka handle base

include/cppkafka/kafka_handle_base.h

@@ -46,6 +46,7 @@
 #include "configuration.h"
 #include "macros.h"
 #include "logging.h"
+#include "queue.h"
 
 namespace cppkafka {
 
@@ -239,6 +240,19 @@ public:
      */ 
     const Configuration& get_configuration() const;
 
+#if RD_KAFKA_VERSION >= RD_KAFKA_ADMIN_API_SUPPORT_VERSION
+    /**
+     * \brief Gets the background queue
+     *
+     * This translates into a call to rd_kafka_queue_get_background
+     *
+     * \return The background queue
+     */
+    Queue get_background_queue() const {
+        return Queue::make_queue(rd_kafka_queue_get_background(handle_.get()));
+    }
+#endif
+
     /**
      * \brief Gets the length of the out queue 
      *

include/cppkafka/macros.h

@@ -46,5 +46,6 @@
 // See: https://github.com/edenhill/librdkafka/issues/1792
 #define RD_KAFKA_QUEUE_REFCOUNT_BUG_VERSION 0x000b0500 //v0.11.5.00
 #define RD_KAFKA_HEADERS_SUPPORT_VERSION 0x000b0402 //v0.11.4.02
+#define RD_KAFKA_ADMIN_API_SUPPORT_VERSION 0x000b0500 //v0.11.5.00
 
 #endif // CPPKAFKA_MACROS_H