libbpf: Skip DWARF sections in linker sanity check

clang can generate (with -g -Wa,--compress-debug-sections) 4-byte
aligned DWARF sections that declare themselves to be 8-byte aligned in
the section header.  Since DWARF sections are dropped during linking
anyway, just skip running the sanity checks on them.

Reported-by: Sergei Trofimovich <slyich@gmail.com>
Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Alyssa Ross <hi@alyssa.is>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Closes: https://lore.kernel.org/bpf/ZXcFRJVKbKxtEL5t@nz.home/
Link: https://lore.kernel.org/bpf/20231219110324.8989-1-hi@alyssa.is