heap: fix build failure due to missing header

Closes https://github.com/espressif/esp-idf/issues/1881

Signed-off-by: Mahavir Jain <mahavir@espressif.com>

components/heap/multi_heap_platform.h

@@ -63,6 +63,7 @@ inline static void multi_heap_assert(bool condition, const char *format, int lin
                       __LINE__, (intptr_t)(ADDRESS))
 
 #ifdef CONFIG_HEAP_TASK_TRACKING
+#include <freertos/task.h>
 #define MULTI_HEAP_BLOCK_OWNER TaskHandle_t task;
 #define MULTI_HEAP_SET_BLOCK_OWNER(HEAD) (HEAD)->task = xTaskGetCurrentTaskHandle()
 #define MULTI_HEAP_GET_BLOCK_OWNER(HEAD) ((HEAD)->task)