bpf: fix link error without CONFIG_NET

I ran into this link error with the latest net-next plus linux-next
trees when networking is disabled:

kernel/bpf/verifier.o:(.rodata+0x2958): undefined reference to `tc_cls_act_analyzer_ops'
kernel/bpf/verifier.o:(.rodata+0x2970): undefined reference to `xdp_analyzer_ops'

It seems that the code was written to deal with varying contents of
the arrray, but the actual #ifdef was missing. Both tc_cls_act_analyzer_ops
and xdp_analyzer_ops are defined in the core networking code, so adding
a check for CONFIG_NET seems appropriate here, and I've verified this with
many randconfig builds

Fixes: 4f9218aaf8a4 ("bpf: move knowledge about post-translation offsets out of verifier")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

kernel/bpf/verifier.c

@@ -4588,8 +4588,10 @@ err_free_env:
 }
 
 static const struct bpf_verifier_ops * const bpf_analyzer_ops[] = {
+#ifdef CONFIG_NET
 	[BPF_PROG_TYPE_XDP]		= &xdp_analyzer_ops,
 	[BPF_PROG_TYPE_SCHED_CLS]	= &tc_cls_act_analyzer_ops,
+#endif
 };
 
 int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops,