compile with libnl-2.1 headers

[Gery Kahn]

while compile iw with current git of libnl-2.1 found that:
  CC   iw.o
In file included from /work/bb/Angstrom/include/netlink/handlers.h:19,
                  from /work/bb/Angstrom/include/netlink/netlink.h:32,
                  from /work/bb/Angstrom/include/netlink/genl/genl.h:15,
                  from iw.c:17:
/work/bb/Angstrom/include/netlink/netlink-kernel.h:9: error: redefinition of 'struct sockaddr_nl'
/work/bb/Angstrom/include/netlink/netlink-kernel.h:33: error: redefinition of 'struct nlmsghdr'
/work/bb/Angstrom/include/netlink/netlink-kernel.h:173: error: redefinition of 'struct nlmsgerr'
/work/bb/Angstrom/include/netlink/netlink-kernel.h:182: error: redefinition of 'struct nl_pktinfo'
/work/bb/Angstrom/include/netlink/netlink-kernel.h:229: error: redefinition of 'struct nlattr'
make: *** [iw.o] Error 1

Fix it :) by comment in netlink/handlers.h line
#include <netlink/netlink-kernel.h>