selftests/bpf: Add a selftest to check for incorrect names

Add selftest for cases where btf_name_valid_section() does not properly
check for certain types of names.

Suggested-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
Link: https://lore.kernel.org/r/20240831054742.364585-1-aha310510@gmail.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>