bpf, tests: Add BPF_JMP32 test cases

An eBPF JIT may implement JMP32 operations in a different way than JMP,
especially on 32-bit architectures. This patch adds a series of tests
for JMP32 operations, mainly for testing JITs.

Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210809091829.810076-2-johan.almbladh@anyfinetworks.com