selftests/bpf: Mark tests that require unaligned memory access

A lot of tests require unaligned memory access to work. Mark the tests
as such, so that they can be avoided on unsupported architectures such
as RISC-V.

Signed-off-by: Björn Töpel <bjorn.topel@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Luke Nelson <luke.r.nels@gmail.com>
Link: https://lore.kernel.org/bpf/20201118071640.83773-4-bjorn.topel@gmail.com

selftests/bpf: add selftests for wide loads

Mirror existing wide store tests with wide loads. The only significant
difference is expected error string.

Cc: Yonghong Song <yhs@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

selftests/bpf: rename verifier/wide_store.c to verifier/wide_access.c

Move the file and rename internal BPF_SOCK_ADDR define to
BPF_SOCK_ADDR_STORE. This selftest will be extended in the next commit
with the wide loads.

Cc: Yonghong Song <yhs@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>