tc, bpf: improve verifier logging

tc, bpf: improve verifier logging

With a bit larger, branchy eBPF programs f.e. already ~BPF_MAXINSNS/7 in
size, it happens rather quickly that bpf(2) rejects also valid programs
when only the verifier log buffer size we have in tc is too small.

Change that, so by default we don't do any logging, and only in error
case we retry with logging enabled. If we should fail providing a
reasonable dump of the verifier analysis, retry few times with a larger
log buffer so that we can at least give the user a chance to debug the
program.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.r.fastabend@intel.com>