libbpf: support BTF_KIND_FLOAT during type compatibility checks in CO-RE

Add BTF_KIND_FLOAT support when doing CO-RE field type compatibility check.
Without this, relocations against float/double fields will fail.

Also adjust one error message to emit instruction index instead of less
convenient instruction byte offset.

Fixes: 22541a9 ("libbpf: Add BTF_KIND_FLOAT support")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

tools/lib/bpf/libbpf.c

@@ -5141,6 +5141,7 @@ static int bpf_core_fields_are_compat(const struct btf *local_btf,
 
 	switch (btf_kind(local_type)) {
 	case BTF_KIND_PTR:
+	case BTF_KIND_FLOAT:
 		return 1;
 	case BTF_KIND_FWD:
 	case BTF_KIND_ENUM: {
@@ -6245,8 +6246,8 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
 	/* bpf_core_patch_insn() should know how to handle missing targ_spec */
 	err = bpf_core_patch_insn(prog, relo, relo_idx, &targ_res);
 	if (err) {
-		pr_warn("prog '%s': relo #%d: failed to patch insn at offset %d: %d\n",
-			prog->name, relo_idx, relo->insn_off, err);
+		pr_warn("prog '%s': relo #%d: failed to patch insn #%zu: %d\n",
+			prog->name, relo_idx, relo->insn_off / BPF_INSN_SZ, err);
 		return -EINVAL;
 	}