Fix potential memory leak in the Win32 FreeRTOS+TCP network interface initialisation sequence.

Introduce portMEMORY_BARRIER() macro to assist with memory access ordering when suspending the scheduler if link time optimization is used.

FreeRTOS/Source/tasks.c

@@ -2104,6 +2104,7 @@ void vTaskSuspendAll( void )
 	post in the FreeRTOS support forum before reporting this as a bug! -
 	http://goo.gl/wu4acr */
 	++uxSchedulerSuspended;
+	portMEMORY_BARRIER();
 }
 /*----------------------------------------------------------*/