[1818] Report the error code when CC_ASYNC_READ_FAILED is logged

src/lib/cc/cc_messages.mes

@@ -14,7 +14,7 @@
 
 $NAMESPACE isc::cc
 
-% CC_ASYNC_READ_FAILED asynchronous read failed
+% CC_ASYNC_READ_FAILED asynchronous read failed (error code = %1)
 This marks a low level error, we tried to read data from the message queue
 daemon asynchronously, but the ASIO library returned an error.
 

src/lib/cc/session.cc

@@ -249,7 +249,7 @@ SessionImpl::internalRead(const asio::error_code& error,
         }
         user_handler_();
     } else {
-        LOG_ERROR(logger, CC_ASYNC_READ_FAILED);
+        LOG_ERROR(logger, CC_ASYNC_READ_FAILED).arg(error.value());
         isc_throw(SessionError, "asynchronous read failed");
     }
 }