bpftool: Update btf_dump__new() and perf_buffer__new_raw() calls

Use v1.0-compatible variants of btf_dump and perf_buffer "constructors".
This is also a demonstration of reusing struct perf_buffer_raw_opts as
OPTS-style option struct for new perf_buffer__new_raw() API.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211111053624.190580-10-andrii@kernel.org