Add selftest validating various aspects of statically linking functions:
- no conflicts and correct resolution for name-conflicting static funcs;
- correct resolution of extern functions;
- correct handling of weak functions, both resolution itself and libbpf's
handling of unused weak function that "lost" (it leaves gaps in code with
no ELF symbols);
- correct handling of hidden visibility to turn global function into
"static" for the purpose of BPF verification.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210423181348.1801389-16-andrii@kernel.org
