bpf, tests: Add tail call test suite

While BPF_CALL instructions were tested implicitly by the cBPF-to-eBPF
translation, there has not been any tests for BPF_TAIL_CALL instructions.
The new test suite includes tests for tail call chaining, tail call count
tracking and error paths. It is mainly intended for JIT development and
testing.

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/20210809091829.810076-15-johan.almbladh@anyfinetworks.com