udp_tunnel_core.c hasn't use any macro or function declared in udp.h, types.h,
and net_namespace.h. Thus, these files can be removed from udp_tunnel_core.c
safely without affecting the compilation of the net module.
Signed-off-by: NMianhan Liu <liumh1@shanghaitech.edu.cn>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>