selftests: bpf: functional and min/max reasoning unit tests for JMP32

This patch adds unit tests for new JMP32 instructions.

This patch also added the new BPF_JMP32_REG and BPF_JMP32_IMM macros to
samples/bpf/bpf_insn.h so that JMP32 insn builders are available to tests
under 'samples' directory.

Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>