Networking: Compile error if Unix domain sockets selected; Update SAME70-xplained README me.

configs/same70-xplained/README.txt

@@ -898,11 +898,20 @@ Click Shield
   some extra Arduino connectors to raise the Click shield so that it clears
   the RJ45.
 
+  This may be a problem only for me because the Arduino connectors that I
+  soldered onto the SAME70-Xplained are short (around 10mm clearance from
+  the board).  Taller headers might clear the RJ45 connector (around 15mm).
+
   NOTE:  Mikroelektronika provides two different click shields:  A UNO style
-  shield with two click mikroBUSes and a larget Mega shield with three
+  shield with two click mikroBUSes and a larger Mega shield with three
   click mikroBUSes.  The above discusses on the UNO shield.  I know that the
   serial ports, at least, differ on the two shields.
 
+  UPDATE: And it appears the that Mega shield is *not* compatible with the
+  SAME70-Xplained.  I am told that the SPI in mikroBUS slots does not connect
+  to pins on the  SAME70-Xplained that can support the SPI communications.
+  Avoid this triple mikroBUS shield!
+
 Tickless OS
 ===========
 

net/netdev/netdev_register.c

@@ -52,6 +52,7 @@
 #include <net/ethernet.h>
 #include <nuttx/net/netdev.h>
 #include <nuttx/net/arp.h>
+#include <nuttx/net/tcp.h>
 
 #include "utils/utils.h"
 #include "igmp/igmp.h"