libbpf: Add API to get/set log_level at per-program level

Add bpf_program__set_log_level() and bpf_program__log_level() to fetch
and adjust log_level sent during BPF_PROG_LOAD command. This allows to
selectively request more or less verbose output in BPF verifier log.

Also bump libbpf version to 0.7 and make these APIs the first in v0.7.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211201232824.3166325-3-andrii@kernel.org

src/libbpf.c

@@ -8475,6 +8475,20 @@ int bpf_program__set_flags(struct bpf_program *prog, __u32 flags)
 	return 0;
 }
 
+__u32 bpf_program__log_level(const struct bpf_program *prog)
+{
+	return prog->log_level;
+}
+
+int bpf_program__set_log_level(struct bpf_program *prog, __u32 log_level)
+{
+	if (prog->obj->loaded)
+		return libbpf_err(-EBUSY);
+
+	prog->log_level = log_level;
+	return 0;
+}
+
 #define SEC_DEF(sec_pfx, ptype, atype, flags, ...) {			    \
 	.sec = sec_pfx,							    \
 	.prog_type = BPF_PROG_TYPE_##ptype,				    \