tools: bpf_jit_disasm: Handle large images.

Dynamically allocate memory so that JIT images larger than the size of
the statically allocated array can be handled.

Signed-off-by: David Daney <david.daney@cavium.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>