libbpf: Use 100-character limit to make bpf_tracing.h easier to read

Improve bpf_tracing.h's macro definition readability by keeping them
single-line and better aligned. This makes it easier to follow all those
variadic patterns.

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/20211222213924.1869758-2-andrii@kernel.org