selftests/bpf: Test gotol with large offsets

Test gotol with offsets that don't fit into a short (i.e., larger than
32k or smaller than -32k).

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20240102193531.3169422-4-iii@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>