Sync FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP with the version in GitHub at (23665258cabe49d5d68ba23968b6845a7c80eb34).

Notes: 
- header has version 2.2.0. 
- This sync did not bring in ./test directory, though we should. 
- New NetworkInterfaces are introduced by this merge.
- Keil compiler support. 
- FreeRTOS_IP.h new API xApplicationGetRandomNumber().
- FreeRTOS_IP_Private.h new eIPEvent_t eNetworkTxEvent. 
- FreeRTOS_Stream_Buffer.h removing static xStreamBufferIsEmpty() and xStreamBufferIsFull().
- FreeRTOSConfigDefaults.h provides default ipconfigDNS_RECEIVE_BLOCK_TIME_TICKS. 
- other type changes.

FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP/portable/NetworkInterface/board_family/NetworkInterface.c

@@ -0,0 +1,63 @@
+/*
+FreeRTOS+TCP V2.0.11
+Copyright (C) 2018 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+ http://aws.amazon.com/freertos
+ http://www.FreeRTOS.org
+*/
+
+/* FreeRTOS includes. */
+#include "FreeRTOS.h"
+#include "list.h"
+
+/* FreeRTOS+TCP includes. */
+#include "FreeRTOS_IP.h"
+
+/* If ipconfigETHERNET_DRIVER_FILTERS_FRAME_TYPES is set to 1, then the Ethernet
+driver will filter incoming packets and only pass the stack those packets it
+considers need processing. */
+#if( ipconfigETHERNET_DRIVER_FILTERS_FRAME_TYPES == 0 )
+#define ipCONSIDER_FRAME_FOR_PROCESSING( pucEthernetBuffer ) eProcessBuffer
+#else
+#define ipCONSIDER_FRAME_FOR_PROCESSING( pucEthernetBuffer ) eConsiderFrameForProcessing( ( pucEthernetBuffer ) )
+#endif
+
+BaseType_t xNetworkInterfaceInitialise( void )
+{
+    /* FIX ME. */
+    return pdFALSE;
+}
+
+BaseType_t xNetworkInterfaceOutput( NetworkBufferDescriptor_t * const pxNetworkBuffer, BaseType_t xReleaseAfterSend )
+{
+    /* FIX ME. */
+    return pdFALSE;
+}
+
+void vNetworkInterfaceAllocateRAMToBuffers( NetworkBufferDescriptor_t pxNetworkBuffers[ ipconfigNUM_NETWORK_BUFFER_DESCRIPTORS ] )
+{
+    /* FIX ME. */
+}
+
+BaseType_t xGetPhyLinkStatus( void )
+{
+    /* FIX ME. */
+    return pdFALSE;
+}

FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP/portable/NetworkInterface/board_family/ReadMe.txt

@@ -0,0 +1 @@
+Update NetworkInterface.c and include other files needed by FreeRTOS+TCP here.