Adding read_build_id function that parses out build id from
specified binary.

It will replace extract_build_id and also be used in following
changes.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230331093157.1749137-3-jolsa@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>