[tcpip] Allow for architecture-specific TCP/IP checksum routines

Calculating the TCP/IP checksum on received packets accounts for a
substantial fraction of the response latency.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/arch/x86/include/bits/tcpip.h

@@ -0,0 +1,12 @@
+#ifndef _BITS_TCPIP_H
+#define _BITS_TCPIP_H
+
+/** @file
+ *
+ * Transport-network layer interface
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#endif /* _BITS_TCPIP_H */