[Swan] Compiling on Ubuntu 16.04

[Paul Wouters]

On Sun, 12 Aug 2018, Whit Blauvelt wrote:

> /usr/src/libreswan/programs/pluto/kernel_pfkey.c:754:13: error: ‘pfkey_register_proto’ defined but not used [-Werror=unused-function]
> static void pfkey_register_proto(unsigned int sadb_register,

I pushed a fix for that. XFRM/NETKEY no longer uses this function, so
it was throwing an error when using USE_KLIPS=false which the debian
build uses.

Paul