selftests/bpf: Add regression test for pruning fix

Add a test to ensure we do mark_chain_precision for the argument type
ARG_CONST_ALLOC_SIZE_OR_ZERO. For other argument types, this was already
done, but propagation for missing for this case. Without the fix, this
test case loads successfully.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220823185500.467-1-memxor@gmail.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>