Fix MQTT multitask demo build (#1214)

* Fix MQTT multitask demo build

* Fix formatting

* Update FreeRTOS-Plus/Demo/Common/coreMQTT_Agent_Interface/freertos_command_pool.c

Co-authored-by: Gaurav-Aggarwal-AWS <33462878+aggarg@users.noreply.github.com>

---------

Co-authored-by: Gaurav-Aggarwal-AWS <33462878+aggarg@users.noreply.github.com>

FreeRTOS-Plus/Demo/Common/coreMQTT_Agent_Interface/freertos_command_pool.c

@@ -41,6 +41,9 @@
 #include "freertos_command_pool.h"
 #include "freertos_agent_message.h"
 
+/* Demo config include. */
+#include "demo_config.h"
+
 /*-----------------------------------------------------------*/
 
 #define QUEUE_NOT_INITIALIZED    ( 0U )

FreeRTOS-Plus/Demo/coreMQTT_Windows_Simulator/MQTT_Multitask/demo_config.h

@@ -293,4 +293,10 @@ extern void vLoggingPrintf( const char * pcFormatString,
     #define democonfigMQTT_LIB    "core-mqtt@"MQTT_LIBRARY_VERSION
 #endif
 
+/**
+ * @brief The number of command structures to allocate in the pool
+ * for the agent.
+ */
+#define MQTT_COMMAND_CONTEXTS_POOL_SIZE    10
+
 #endif /* DEMO_CONFIG_H */