gcc < 4.6 does not handle C11 syntax for the static initialization of
anonymous struct/union, hence the following error:

tc_bpf.c:260: error: unknown field map_type specified in initializer
Signed-off-by: Julien Floret <julien.floret@6wind.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>